I published my first app in the iPhone App Store a little while back, here are a few loose thoughts on the matter:
Approval process takes too long.
It took a week to get initially approved for my app and an update I put in for took about the same. It's a very discouraging process to have to go through. It'd really be nice if the initial approval took a week and you get a pass on updates. I know that opens them up for abuse, but couldn't I just sign one of those 'on my honor' deals that I won't violate their trust?
Feedback can be a bugger to get from users.
Feedback is really important to a developer as far as features, bugs, etc. Unfortunately, the only standard opportunity for people to do that inside the iPhone is when people delete the app. This of course is fine, except that the only feedback you get is a star rating. There are a few people that go out of their way to give good (as in qualitative) feedback, but they're far and few between. I've seen a few apps that nag you for rating and that gets old, even when you leave the app to do so.
Not a big 'community' for Objective-C
Objective-C has definitely climbed up the ranks in popularity since the iPhone debuted, but a big marker of a strong language is reflected in the community that springs up. Java and .NET are good examples of a thriving development community that look out for one another. StackOverflow is a good place where there are tons of great questions/answers on how to do things in those respective languages, but I really don't see the same in Objective-C. The communities themselves are one of the best resources for how-tos and troubleshooting, but they're also great for learning new patterns in software development.
Eclipse and Visual Studio have spoiled me rotten
The IDE is where all the magic happens. Unfortunately, XCode is no where near as polished as Eclipse and Visual Studio. If Apple were to choose one place to improve the platform, it'd be to juice up its IDE with better Intellisense, code generation (why do I have to manually write the synthesize properties???), etc.