Since it seems to be the popular thing to do lately…

• The industrial design is brilliant, but doesn’t look as awesome in non-perfectly-lit real life – we all know how powerful the photoshop makeover can be but for some reason this time the gap seems to be disproportionately huge. It doesn’t feel as narrow as I thought it would based on the photos.
• The display is awesome. Naming strategy aside, any 300+DPI screen, be it LCD or LED, is going to get my attention in a great way. I have near 20/20 vision; I can’t discern the pixels at the closest distance my eye will continue to focus (about 3 inches). The brightness is not as blinding as I expected, but it does retain LCD’s in-sunlight visibility.

  Photos look good, but text is where the difference really pops out at you. Fortunately it’s not an obnoxious kind of difference – you just notice the letterforms really look the way they’re supposed to.

  Another thing that was obvious at launch: folders are a much nicer feature when you can actually discern the icons of the contents – you can actually read the word “TIME” in the in-folder icon for the app.

• As others have noted, it does feel slightly faster than the 3GS, but I don’t think it’s enough to get excited over. The 512MB of RAM should help considerably with multitasking.
• Haven’t made a FaceTime call yet, so not much to say about that.
• The new cameras have not been mindblowingly better in indoor photos than the 3GS’s excellent autofocus camera. (This observation is contrary to what Marco Arment has to say about it.) The flash is a welcome addition and, unlike seemingly most other phones, does not add a gigantic hideous appendage to the handset. The front-facing camera is… well, good enough for what it needs to do.
• After hearing about the touching-bottom-left-signal-degradation issue, I decided to get the bumper case. It was available today only in black; whatever, I’m not picky. The metal buttons on it are very classy and the design adds very minimal bulk. I don’t like how much it recesses the mute switch, but that’s probably just because switching silent off and on is an idle habit of mine.
• Speaking of the silent switch: it is pretty, but I don’t like the feeling of it as much as the 3GS’s. The volume and power buttons also feel really tense – hopefully with a few days use they will loosen up and feel more friendly.
• I always gotta have the dock – one expensive habit. I don’t like this one nearly as much as the 3G/3GS’s – having the entirety of your iPhone’s front face on display was really something special and the new one takes that away. In a bit of déja vu, the bumper case and dock are utterly incompatible. I’m erring towards using the bumper rather than the dock at the moment, but we’ll see how that changes once it’s not brand new. Very much an aside, but the packaging for the dock seems even smaller this year than before – Apple seems to still be taking the packaging-reduction initiative to heart.

All in all, I don’t feel like this is a must-have upgrade that everyone should be signing up for as soon as possible. As front-facing camera apps get to be more popular, that functionality will start to show value – same with Retina Display apps. It’s a similar situation to the iPad – the hardware is different in substantial ways, but it really is the third-party applications that make the iPhone the powerhouse platform it is. The iPad has been out for a few months now and still has a ways to go in terms of finding its set of killer apps; I expect the iPhone 4 side may move a bit faster given the size of the upgrade base and the lower level of expectations as far as change of functionality given it has the same form factor.

The biggest question that remains unanswered for me in the Android-iPhone battle is a single feature: screen size. The larger 4.3″ screens on recent Android phones seem to be made solely to out-spec the iPhone on the display front and count themselves as HD. Yet now, they’re outclassed on resolution as well. I can’t imagine holding one of those comfortably in a single hand. Perhaps I’m mistaken and mobile hotspot functionality is a must-have for a bulk of consumers in the United States, but barring that, I echo Engadget’s sentiments: this reinforces Apple’s dominant posturing in the smartphone arena. There are things it lacks, but at the end of the day, they’re things you’d rather live without the few times you’d need them than put up with many tiny quirks on a daily basis.

postscript: I tested the “left corner signal degradation” situation earlier; it seems that if you don’t give your phone the death grip, signal is affected minimally. It also seems to be intermittent – sometimes you can just put a sweaty palm to the corner and have no degradation, and sometimes putting a few fingers on it lightly is enough to take you from 5 bars to 1. I don’t know if it affects actual call or data quality; some have said that it does not.