tl;dr: The iPhone 4 is another great step forward from Apple. From the dazzling quality of the built-in camera and respective app, to the brilliance of the Retina display, this iPhone is an all-around winner.
After having tried an iPhone 4 display model at my local Apple Store, and tasting the Retina display kool-aid, I couldn't wait until my pre-ordered unit finally came in. Well, it did, and I have to say that one day's use has already impressed me enough to look on older iPhones with some amount of disgust. How could I have possibly coped with the low-resolution display, grainy camera, and rather sluggish upload speeds on the 3G and 3Gs?
I have experienced great clarity in calls on my iPhone 4, both on my and the receiver's end. This is likely due to the fact that the iPhone 4 now has a noise-cancellation microphone on top, which helps to filter out background and static noise while on a call.
The speaker (for speakerphone or listening to music out loud) is on-par with my iPhone 3Gs, and the earpiece is about the same, too.
Everything else is about the same as the iPhone 3G/3Gs. Nothing much to report here.
None to report, so far. A lot of people have made a large amount of noise over this issue... and I can replicate the odd problem of signal loss when holding the iPhone 4 a certain way... but (a) this has not been a problem for me so far in one day's use, and (b) it has only happened in a few different places. At home, I can't replicate the problem. Go figure.
Gorgeous. Need I say more? You really, really really have to see one in-person to appreciate it. No picture viewed on your computer (or any other current LCD, LED, or CRT display) can possibly do the Retina display's quality and sharpness justice.
Camera Quality (Stills)
I am what may be called a reluctant amateur photographer. Reluctant, because I really wish I could be a professional. Amateur, because I have neither the time nor the equipment required to be a true 'professional.' However, I have been privileged to shoot with pro cameras and lenses on multiple occasions, and I have (in my opinion) very high standards for 'keeper' photos (photos that aren't immediately trashed after importing into Aperture).
Since purchasing the Canon PowerShot G11, I have been using it as a walkaround camera during short trips, family parties, and similar occasions (rather than carrying around my Nikon D90 + lenses/flashes). I have always been one to consolidate, though, and as soon as the iPhone came out, I ditched my old Palm m505 PDA and separate cell phone. But camera phones have never been good enough to let me set down my point and shoot. Until now.
This iPhone takes gorgeous pictures in good lighting. Even the background is exposed pretty well, even if there's some image noise. I'm extremely glad Apple's following Canon and Nikon's lead, and focusing on per-pixel image quality rather than megapixel insanity. While other companies are pushing tiny 1/10" sensors to 6, 8 or 10 megapixels, Apple increased the size of the camera sensor and stuck with 5 megapixels, so images retain pretty good image quality.
While not noise-free, like an ISO 80 shot on my G11 in good lighting (or, heck, ISO 400 on my D90!), the iPhone produces perfectly acceptable shots in most situations. Meaning I have one less digital device to lug around!
I also tested the iPhone in almost pitch-black lighting—the image below was taken using only the light from a fireworks display:
Two other things that allow me to use the iPhone as a walkaround camera: almost zero shutter lag, and a pretty quick shutter speed—I can take maybe 1.2 pictures per second - almost as good as my G11 (but nowhere near the nice 11 pictures/second of the Nikon D3 I love so much).
Camera Quality (HD Video)
For the past few years, I tried my hand at shooting video on my Nikon D90 (it shoots in 720p HD with a mono mic, but has few adjustments/controls), but found it much too cumbersome. The iPhone almost matches my D90's HD video quality (at least, in typical situations... I can't put a 50mm f/1.4 on the iPhone to get a beautiful depth-of-field effect!), and is in my pocket.
[Related: See my blog post on using external mics with the iPhone 4's Camera app].
See the video below, which was completely shot and edited in iMovie on the iPhone:
(Click through to YouTube or click the HD button to see the 720p video quality).
A bonus feature of the video mode is that you can turn on the included LED light and use it as a flashlight—a very, very bright flashlight that gets noticeably warm after about 5 minutes of use! But this is much nicer than using the front screen of the iPhone for the purpose. I hope a good flashlight app (one that simply turns on the LED when the app is opened) is released soon!
- The phone feels great in the hand, and fits a few of my old iPhone 3Gs accessories. Unfortunately, a lot of my old accessories were molded for the 3G/3Gs, so I can't transfer them to the new iPhone 4.
- All my apps are working great on the new iPhone 4, but a few of the icons, and many in-app graphics/icons look pixelated on the otherwise-gorgeous Retina display.
- The new iPhone 4 dock is rather annoying in that it has a small slit of plastic that very slightly encumbers the use of the iPhone in-dock. The 3G/3Gs dock let your finger run over the entire surface of the iPhone. Not a huge deal, though; just an annoyance.
- Both the front and back now need a shirt-wiping every day (at a minimum). They'll both pick up your smudges pretty easily. I might invest in a thin case for this iPhone... I don't particularly like the bumpers Apple offers (especially at $29).
- The sleep/wake button and volume up/down buttons are much more solid and easy to use. However, I'm not a huge fan of the metal silent/ring switch - it now requires a fingernail to activate (unlike the 3G/3Gs). Another minor annoyance...
The iPhone 4 can be purchased used for around $200 as of 2013.