To be honest there have been no wow moments for me.
Really excited to get the phone and unbox it that was about all. As soon as i touched the screen for the first time my jaw dropped. It was no where near as smooth and responsive as my HTC HERO.
Had no problems initially but after 48 hrs of playing with it i realised that the phone side of the software is poor. Yes i know people say well its not a phone really blah blah, but the reception is really poor and it constantly dropped calls.
Found the phone uncomfortable to hold for long periods due to its thickness. The software is buggy and i know it will get better but with the battery issues, the poor touch functionality, the slow response and the size of the thing it just had to go.
Bring on the motorola milestone. Got it today and its a dream in comparison. The screen is beautiful and it all seems to work as it should. Slightly faster than my (OLD) Hero and with crystal clear clarity on phone calls. The speaker is hellish loud.

So in a nut shell im returning my n900 to nokia under the 14 day im not happy guarantee, selling my HERO and continuing to drewl over my milestone. Love it , just Love it.