OS 3.0 LagAll apps seem to take much longer to load/unload after the OS 3.0 update. Laaaaaaaag.
Battery DrainTo be honest, I don't mind this so much anymore given the iPhone's spectacular display and powerful applications. You can't have your cake and eat it, too, right?
Categorizing AppsOr the complete lack thereof. Give me a way to categorize my apps, please. Having to type in the app name via Spotlight or scrolling through every single screen isn't efficient.
Also, how about something like a "bin" to temporarily place all my apps that are on the back burner? I don't necessarily want to delete them, but they don't need to be cluttering up screens.
Accessing the Keypad During CallI'm of the opinion that the keypad AND the other options can all be visible on one screen. The lack of physical feedback is bad enough--why would the designers also want to hide the keypad and force me to manage states while I'm on a call? There's plenty of space available!
Speakerphone VolumeThe speakerphone volume is too low. Why can't it blare loudly just like when I'm playing songs with the iPod app? And NO, I'm NOT using speakerphone in public...
Shutter Release ButtonTrying to take a one-handed photo is tough on the iPhone. You have to balance the device while trying to depress the shutter release button. Couldn't the designers just overlay the button on the top-right or top-left side of the camera (depending on whether you're left-handed or right-handed) where your thumb would naturally rest instead of the 90 degree angle required at the bottom?
Note: The shutter takes way too long... lag.
EmojiIt must be some conspiracy by the Japanese technorati to keep emoji out of foreign hands. Because obviously those outside of Japan could never harness the awesome power that comes with using cute, expressive emoticons... WTF Apple?
SpotlightIt's a neat little search, but I don't use it all that much... Does it really need to be it's own home screen? Just make it an app (or at least have the option for this). I hate over-swiping the app pages and ending up on Spotlight. It forces me to have to back up (and it lags so I gotta wait a second or two before it actually swipes back to the home page).
Entourage and Calendar Sync IssuesI don't know if this is just an issue with my company's email system or something more widespread... Regardless, if you find yourself missing meetings recently, then here's my advice: Don't take any actions via the iPhone's Calendar app. You'll accept the invitation to that really, really important meeting with the boss that's slated for next Tuesday at 9am sharp... only to get no reminder via Entourage (Mac's version of Microsoft Outlook) when the day comes around. In fact, it's nowhere to be seen on your calendar!
I'm not exactly sure who's to blame here--my company, Apple, or Microsoft--but there's no doubt who gets the raw end of the deal: Me.
Landscape OrientationLandscape orientation is actually a nice feature because the iPhone does a great job of adjusting the content smoothly, but I've noticed applications will sometimes get stuck even though I turn the iPhone back to portrait view. Sometimes I've gotta do this little thing where I make sure it's perfectly straight and perpendicular to the ground, maybe move it back and forth slowly between the two views, before it realizes, "Hey, I'm sideways!" Perhaps this is just related to the lag that many have experienced with the 3.0 upgrade, though.
Another common problem is when you're using the iPhone while laying down. While I realize it's not some magical device that can predict your own orientation, the option to turn it off should've been included.