For me 2.0 is a LOT buggier than 1.1.4 was, guess they've added a lot but it's watered down the reliability of it no doubt. I find the biggest issue is Safari crashing, then 3G just not working (failing to load), GSM not picking back up quickly or at all after being on tube, slow and laggy menu's.
I've seen all manner of random things, but an order of magnitude less than what I experienced on my N80 which was quite frankly, unsuable!
Apple have a good history of performance enhancements with OSX, pretty sure that these problems with the menus and typing are a blip in the initial 2.0 firmware and normal service will be resumed shortly.
Have to say I'm bloody impressed with the 3G surfing! Maps has already been a life saver on more than one occasion.