I wouldnt knock HTC, they make good stuff but has always been let down by WM. The latest stuff with Android is very good and the sense UI is a good experience, they just need to expand on the Android based hardware. I can see myself dual booting the N900 with Maemo/ Android at some point.
Probably not skype, it was never integrated with the rest of the system in previous versions.
Multi-tasking! Take that iphone!
I was not happy with volume levels for N800 or N810, especially the latter. I could rarely make out the GPS verbal instructions most of the time over road noise alone. I was informed that the N800 was capable of higher volume but it had been intentionally limited. Never got a good answer as to why though. I just hope the next device is capable of being louder-- let ME decide if it's too loud and turn the volume down myself.
The only thing I don't like is the statusbar. Kinda huge design fail, icons are too disordered. I'd rather do something like this: