I have switched from an iPhone 6s to an iPhone SE a few days ago, and will give you a thorough review on the device and my personal experiences.
Let me give you a little bit of background first. As you might now, I'm a very strong opponent of flat design, and utterly dislike the design of iOS 7 and it successors. I've used an iPhone 5 with iOS 6 until September 2015, when I needed to replace the device because of a broken home button (yes, I know I could have repaired it). However, the new iPhone 6s debuted the iSight camera which makes very good pictures compared to my iPhone 5, so with the Pangu jailbreak known to be just around the corner I gave in and bought an iPhone 6s.
I'll split my review of the iPhone SE into a hardware and a software section.
After using the iPhone 6s every day for a bit more than 10 months, I can honstly say that I am not a fan of the model. Don't get me wrong: the specs are really great! The A9 processor delivers much greater CPU and graphics performance than the A6 of my old iPhone 5. The iShight camera takes way better pictures (even better ones than my first digital camera almost 15 years ago), and when you think of your smartphone as a kind of “pocket computer” that is hardly used as a phone today, the bigger screen real estate is more than welcomed.
The design mistakes of the iPhone 6 and 6s all seem to be linked to my apparent nemesis Jony Ive, Apple's Vice President of Design. Seriously, that guy needs to be fired sky-high! The iPhone 6 and 6s are much thinner than my old iPhone 5, but also a bit wider due to the larger display size. The edges are beveled, and these design choices combined make it surprisingly difficult to pick an iPhone 6s up from a flat table and holding it firmly at its sides. The 6s is also a lot heavier, which adds to a delicate feeling when holding it in one hand. Speaking of one hand, I have rather small hands and cannot reach all areas of the display when using the phone single-handedly. To make things worse, I think the plastic antenna bands on the back of the iPhone 6s look really cheap. It's nothing compared to the refined look of the iPhone 5 and 5s.
So, what has changed for me when moving from an iPhone 6s to a new iPhone SE?
You can imagine how excited I was when Apple announced the iPhone SE. However, it ships with iOS 9.3, so I had to wait until last week when Team Pangu finally published a useable jailbreak tool for the latest iOS version.
It feels like homecoming! The iPhone SE has the exact same casing as the iPhone 5 and 5s, with a few improvements: the aluminum casing is now completely matte brushed and does not have the shiny chamfered edges of its predecessors. The home button has a Touch ID sensor (which is new from an iPhone 5 standpoint), and the device is also available in a rose gold finish (which I personally detest, but makes complete sense marketing-wise). I can hold the iPhone SE firmly in one hand, and can reach every corner of its screen with my thumb. It's a lot lighter than the iPhone 6s, and it feels like a quality device. The aluminum and glass back without any plastic looks great, making the iPhone SE the most refined smartphone design ever! Apple is well advised to keep it indefinately—the huge success with customers supports my claim.
It's interesting that the iPhone SE is much thicker than the iPhone 6s, but at the same time much less noticable in my pocket. I often had trouble to fit both my wallet and an iPhone 6s into the same pocket of my jeans, but during the first days with an iPhone SE I often had the impression that I've lost it.
The back camera takes the same great photos as my iPhone 6s. This came in very handy last weekend for an unexpected photo shooting. The camera does not match my Sony NEX-F3 of course, especially with the new portrait lense that I've bought, but with a bit of Gimp magic the photos turned out really great.
The iPhone SE has a great battery life! I often couldn't make it through the day with my iPhone 6s, but the SE has 30% or 40% of battery life left when I go to bed. I suspect that iOS 9.3.3 is a bit more optimized than iOS 9.0.2, and my jailbreak tweaks surely require additional power as well—but the biggest contributor to the improved battery life will be the much smaller display backlight.
The display size is much smaller in the iPhone SE than in the iPhone 6s: you get the same 4" display with 640×1136 pixel than in the iPhone 5 and 5s. I was worried about being spoiled by my iPhone 6s, but after a day I hardly missed the larger display at all. So no need to worry here!
The iPhone SE hardware also has a few downsides. You are royally compensated for them with a much lower price, though.
Apple builds the same 1.2 megapixel front camera from the iPhone 5 and 5s into the SE model. The camera is good enough for an emergency selfie, but other than that the image quality outright sucks. I take about one selfie a month, so it's no big deal for me.
I got used to the smaller display size real quick, but I have to say that the iPhone SE display is not as good as the newer ones. Don't get me wrong, it's a really great display, but in direct comparison my iPhone 6s delivers a deeper black and more saturated colors. Especially blues appear much better on newer displays—the iPhone SE has a bit of a yellow tint (night shift is disabled, of course). Again, the iPhone SE has a great display regardless, and you probably won't notice anything when you wake up in the morning and look at it.
This issue is also widely discussed, and the consensus is that the adhesive material used for the touchscreen digitizer takes a long time to dry. During this time, it is not quite as clear.
I have a bit of a mixed opinion on the speakers. The iPhone 6s has undoubtedly better speakers than the iPhone 5 and SE, with crystal clear sound and a much better bass. The iPhone SE sounds very tinny compared to it.
There's a big caveat, however: my iPhone 6s always had trouble with its speaker volume. Even at full volume, it was just a bit too quiet. On a few occasions I wanted to throw the damn thing out of my car window: when going 160 km per hour on the German autobahn, the navigation instructions were incomprehensible—even at full volume! Editing the proper .plist configuration file of the iOS Celestial framework helped to set new volume limits helped a bit, but could only do so much compared to my old iPhone 5. The iPhone SE, on the other hand, has got loud speakers like they should be. If I had to decide, I'd take the iPhone SE speakers: what use does a better sound quality have when the volume is far too low?
The last hardware component I'd like to write about is the barometer. I really liked the Health application on my 6s to log my everyday flights of stairs and distance walked. The iPhone SE does not have a barometer, however, so it cannot keep track of the stairs you've climbed! That was a bit of a bummer for me, but then again the iPhone SE is much cheaper—and a barometer certainly is an expendable piece of hardware in a phone!
The iPhone SE comes with a preinstalled iOS 9.3.0. The first thing I did was upgrade it to iOS 9.3.3 because of a security vulnerability regarding the .tiff file format dubbed “Stagefreight”. Several jailbreak tweaks exist to disable this rarely used image file format, but unfortunately I depend on it. I use ProCamera instead of the stock iOS camera app, and have configured it to store all photes as uncompressed .tiff files to avoid any JPEG compression artifacts. iOS 9.3.3 is the first version with a fix.
Upgrading to iOS 9.3.3 has a drawback, though: in case of a broken or lost iPhone, I cannot restore any backup to the stock iOS 9.3.0. Even worse, it will soon be impossible to upgrade any replacement device to iOS 9.3.3: a few days after iOS 10 has been released, Apple will stop signing any previous versions of iOS. It is also unclear at this point if any future version of iOS can be jailbroken. So to make provisions for a hardware defect or stolen device, I've bought a spare iPhone SE and upgraded it to iOS 9.3.3 while this version was still signed by Apple—that's how much I like the device!
Jailbreaking iOS 9.3.3 with the latest Pangu tool went surprisingly smooth. All Cydia tweaks I use are working flawlessly on iOS 9.3.3 now—even though the developers had hardly any time to make adjustments. I was also pleasantly surprised that the settings of all tweaks were automatically transferred to my new device using the iTunes backup—great work!
iOS 9.3.3 seems to be a lot more stable than iOS 9.0.2. My iPhone 6s used to crash almost daily, whereas I had a single respring on the iPhone SE. I also have the impression that iOS 9.3.3 is a bit faster and smoother, although that could be placebo.
Lightning SD card reader
I was very pleasantly surprised to find out that iOS 9.3.3 finally supports the Lighting SD card reader accessory on the iPhone, too! This is a big deal for me, because I usually take my iPad with me on vacation to upload photos taken with my Sony NEX-F3 to Instagram. The iPad can stay at home now because my phone can do the job. This has been due for several years now.
iOS 9.3.3 has got one downfall that I have yet discovered : the Health app. It looks just as ugly as it always did, no doubt about that, but the white line graphs have been changed to orange bars. This makes the graphs a lot harder to read, and I do not have a precise comparison with the previous month or week (that worked well using the lines' angles). Also note that the year view now displays daily averages, not absolute numbers! I found it very intersting to see how far I've walked in an entire month. The Health app is total crap the way it is now (and it's going to be even worse in iOS 10).