1) Not all iPod Accessories and headphones will work with the iPhone: Unless your accessory specifically claims that it works with the iPhone, you're going to have mixed results when you plug in. Some work (but prompt you to turn on Airplane mode), some don't. So far our test show good results.
As for headphones, if you've got an L-shaped plug or a fat plug, you're out of luck. Thanks to the recessed headphone jack, you're going to actually have to buy an adapter to get some of your regular headphones to work with the iPhone.
2) Married to AT&T for 2 years : You know this. Being stuck on AT&T for two years is going to be horrible. Plus, their reception and customer service leave a lot to be desired.
3) No video recording or MMS: The iPhone's 2-megapixel camera is great if there's enough light, but there's no video recording at all. None. This is odd, since the iPhone has so much video playback capabilities in its iPod "app," but don't expect to make movies with this thing. And since you can't record video, you can't send any video messages (MMS) either.
4) No Instant Messaging. (You can try Meebo though)
5) Not for business use: BlackBerry enthusiasts need not apply. In addition to the keyboard being totally different, there's no push email except for Yahoo Mail. There is Exchange support, but it's just using IMAP access.
6) It's not a full iPod Replacement, and it has no games: With 4GB or 8GB of storage, this is essentially an iPod nano. It's definitely not an iPod Video, both in terms of storage and functionality. You can watch videos, sure, but there's no TV out, and not nearly enough room to keep all the TV shows and podcasts you keep downloading. Plus, all those 5G iPod games that you thought were going to make it onto the iPhone? Nope. No games at all.
7) It's not a smartphone: As much as Apple wants you to think their "open application development" using webapps is actual apps, it's not. You can get some stuff done using webapps and Safari, but as of right now, support sucks. Until people start developing apps specifically customized for the iPhone's quirks, you won't be doing anything super fancy.
8) The data connection is slow: Although the iPhone has both EDGE and Wi-Fi, you're probably going to be using EDGE most of the time. Why? Because if you're in Wi-Fi range, you're usually at home or at work, when you've got an actual computer in front of you. When you're outside driving or walking, you'll be on EDGE. If you're on EDGE, expect emails with large attachments and Web pages to download slowly.
9) There's no GPS: The iPhone may have a Google Maps application with turn by turn driving directions, but there's no actual GPS in there. You're going to have find your current location yourself, plus tell the phone exactly when you're turning. Like the data connection, a software update can't fix this.
10) There are no custom ringtones: You can't use your own ringtones (whether they're MP3s, downloaded music, or iTunes tracks) as ringtones for your phone.
As you can see, the iPhone has caveats galore and if any of the other features are important to you, you may have to wait until iPhone 2.0. iPhone is a sexy device and I m confident that the next generation of iPhone will resolve most of the limitations mentioned above. For a first timer in mobile device development, I must say Apple certainly had shaked up the mobile phone industry.
Source : Gizmodo