Most of my disappointment with the N800 was in the operating system and UI. There was absolutely no support either. I don't think it even came with a manual. It looked like it had been cobbled together rather than lovingly thought out.
maemo looked interesting, but even the firmware update method was archaic and extremely over complex. From what I remember it only worked if you unplugged the usb cable and plugged it in at exactly the right point or something! (swear to god, this was in the README).
N900 is interesting in that it is both a tablet PC (or whatever term fits best) and a phone. One less device to carry.
I do not know re. if the UI experience has changed. I can see how N-series tablets can appeal to hackers who like to modify the software that is running on their device. From this POV having a full-fledged Linux on a mobile device is a plus. But N710/N800 was indeed less slick in terms of the user experience than Apple's devices.
