Soon after I first got my iPhone [first generation], perhaps after a few days, I wrote up the following list of criticisms/observations regarding different aspects of the device:

iPhone in General:

• Reception is worse with AT&T than what I was used to with Verizon. I get 1-2 bars at home and a lot of interference, whereas with Verizon I had a perfect signal just about everywhere.
• The phone induces sound in electronic devices with speakers. If I place the phone within 3 feet of my alarm clock, then periodically (every few minutes) the alarm clock will emit an annoying low-pitch morse-code sort of sound. If within 5 feet of my electronic piano keyboard, then when on, the keyboard emits the same sound, even more loudly.
• The virtual keyboard is difficult to type on. A sideways-oriented keyboard option with larger keys, perhaps, would have been better. Or an optimized arrangement (not qwerty) such that keys for letters most likely to be found next to each other in words (weighted by the most common words) would be farthest away from each other on the keyboard.
• The virtual keyboard’s “autocorrect” function is not very good at figuring out what I was intending to type, and I find myself very frequently backspacing.
• It is difficult to position the cursor within text, to make edits. [This is before I learned about the magnifying glass.] The keyboard suffers from a lack of arrow keys. The cursor itself is too small to position accurately with a fingertip, and several input modes prohibit this. So to fix a mistake near the beginning of text, I need to hit “backspace” and erase everything typed subsequently, fix the mistake, then retype.
• The phone crashes frequently in a certain specific location. Perhaps due to electronic interference, the whole unit will freeze up and become wholly unresponsive to the touch screen. I had to find instructions online for how to hard-reboot the phone, and the problem subsequently recurred several times. [I now suspect that this is due to the phone trying to connect to a wireless network with the same SSID as that of my home wireless network, but with a different passphrase.]
• Animation speed should be variable, or it should be possible to turn off animations altogether.

Web Browsing:

• Browser (Safari) does not support Flash or Java.
• I cannot increase text size on a web page independent of width. (I.e., I can only zoom in and out and see parts of the window close-up, not make the window narrower in relation to the text size.) Pages which are very wide are difficult to navigate, because once text is zoomed to a readable size, lines of text are many times wider than the screen, which must be scrolled back and forth horizontally to read content on the page.
• The browser window picker frequently does not save window thumbnail images between “sessions” (i.e., turning the phone off and on). [Actually it seems to be some other algorithm which decides which thumbnails to forget.] This makes having thumbs for each window nearly pointless, as at any given time almost all thumbnails are blank.
• Browser window history is often not saved between sessions. I count on the back button working when I click on a link — but if I lock and unlock the phone, or temporarily stick the phone in my pocket for a bit, Safari seems to have “forgotten” about past pages and back becomes disabled. [This also occurs randomly, and is not specifically due to turning the phone on/off.]
• A page is not rendered while scrolling; the scrolling action needs to be completed before the newly-revealed section of the page is rendered. This makes it feel clumsy to locate sections on a content-full page, when the page is zoomed in.
• Mobile versions of pages, when a website has provided them, cannot be zoomed, no matter how small the mobile site’s text is.
• Window-picker view will not change orientation (from portrait to landscape or vice versa) if the phone is rotated while in that mode, but follows the currently prevailing orientation when entered.

Phone:

• Contact’s photos, when assigned, are not shown in the contact list, only when the details for a contact are opened.

Email:

• There’s no quick way to go back after clicking on a link in an email. The link is opened in Safari, but to get back to the email from which the link was clicked, I must press the “home” button and re-open the email application.

Sounds:

• Speakerphone/ringers are too quiet.
• There’s no “reminder” mode whereby a text message / voicemail / missed call will periodically chime until acknowledged. Granted, most users are probably so in love with their iPhones that they look at them every few minutes to see if something new has happened on the screen, but I’ve missed meetings because the SMS reminder I set up for myself came in while I was walking, or in a noisy place, or had momentarily stepped away from the phone.

Weather:

• The world clock could easily have been completely integrated here. Simply show the local time next to the local weather forecast.

Calculator:

• A more advanced calculator, scientific or graphing, should be available; at least a basic calculator which allows the typing of mathematical expressions, with parentheses, for evaluation.

Now that I’ve had it for several months, I’m comfortable with the functionality, but need to refine a few of my observations.

• Reception is much worse than I had originally thought. Inside my apartment, I can barely hold a conversation. I need to stand in a specific spot in the living room to minimize the frequent cut-outs and static. If a call is dropped (because I’m not standing in the magic spot), I typically won’t be able to call the other person back for a couple minutes while the number of bars on the display is reduced to 0. This cycle repeats itself every 10 – 15 minutes.
• Outside on the street, I usually have perfect reception.
• At work, in my office, I have the same problems as I do at home reception-wise. Spotty signal indoors, perfect outdoors.
• AT&T’s EDGE data network, which the iPhone uses to check email and browse the web, is horribly slow. Picture using a dial-up modem (if you’re old enough). Now think back through older models. Start with 56k, then go back to 33.6k, then to 28.8k. Finally, think of a 14.4k modem. Now take its speed and halve it. Quarter it. That’s about how fast your data will come in, if you’re lucky and have all bars of reception. Otherwise, minutes will go by while a single non-graphics-heavy page finishes loading.
• Google Maps’ map tile data seems to load much faster than the general speed of the data network would allow, judging from Web page loading / email checking performance. Perhaps AT&T prioritizes certain traffic for Apple, somehow?
• While visiting Mexico, I had a nice strong full-bar signal which would have cost me $1 a minute to use. Data was similarly outrageously priced and metered per kilobyte. (Thankfully our hotel had free wi-fi.)
• Battery life isn’t all that great. I drain a little over half the battery in one day’s typical usage. If I forget to charge the battery for one night, the phone will likely die towards the end of the following day.
• The iPod functionality is good, and sound quality is beautiful. It would be nice if Internet radio stations were available, though. (This wouldn’t work over EDGE, obviously, but could easily work through wi-fi.) It would also be nice if podcasts were supported. (Here, EDGE would work just fine, as it doesn’t matter how slowly podcast data trickles in.)
• The iPhone’s OS isn’t particularly stable. I’ve crashed the phone many times and needed to hard-reboot it by holding down both buttons for several seconds. Individual applications also crash if something is clicked incorrectly, and there’s no way to restart an app — although here, the phone can be powered down nicely just by holding down the “off” button on top of the device.
• I don’t like the necessity of hitting the “home” button to switch applications, and would prefer an area on the screen I could tap.
• The phone itself is uncomfortable to hold to my ear.

Granted, most of these (besides the data rate, reception, and crashing issues) are nitpicky criticisms from a UI perfectionist, not things which particularly bother me. Just things I’ve noted. (And I could have gone on, but this list had gotten long enough.) Indeed the complexity and level of functionality of the device itself is what even enabled this criticism to have been possible in the first place. Standards are higher, and this phone is more ambitious than anything else out there, at least currently, at least as far as I know. Also, I’ve never been a big fan of “the Apple way”, so some of this (lack of more detailed configurability such as not being able to turn off animations; an overall tradeoff of speed and snappiness in favor of polish and pixel-perfect drop-shadows) is old hat.

After all this, I’m glad I bought an iPhone. I’m also glad I opted out of the two-year contract and into a pay-as-you-go plan.