I'm admittedly underwhelmed by iMessage.
I expected a seperate function with unique IDs for every i-Device similar to BBM.
But on the iPhone it's just in the texting app. And it's by your Apple ID. So if you have an iPad and an iPhone both authorized with the same apple ID (but being used by different people in the same household) it's like you're texting yourself.
Other things have been strange trying to sort out or get how I wanted them to be and whatever else. Like the Camera button on the lock screen only appears when you make the iPod controls appear.
I also don't like Videos and Music being two separate apps like they are on the iPod touch.
They consolidated some things which I wish hadn't been (text messaging and iMessage) and split other things that shouldn't have been.
Newsstand should also be able to be put away somewhere (hidden in a folder of stupid apple stuff I can't delete). I plan on never subscribing to anything in Newsstand. I don't even use iBooks and now this 'newsstand' thing is essentially duplicating it in a more annoying way.
And stocks are ALL OVER THE PLACE. Why? I don't want to see the stocks app at all. I don't want to see stocks in my notification centre. It's just annoying.
I'm happy to finally be able to set custom tones for things like emails, texts, etc.
iCloud looks somewhat promising.
Wireless syncing is great.