I have to echo this. In fact, I had the chance to use a N900 just a couple of days ago. I'm not going to lie, it's a gigantic piece of junk, let me enumerate the ways:
- Resistive touchscreen in this day and age? The light touches that I can use on every Android phone and iPhone turn into concerted screen-mashing on the Nokia. The drags and flicks that have become popular (and important) gestures are hard to do on the N900, if not impossible, because the hardware itself simply isn't up to the task.
- The UI was painfully, ridiculously slow. IMHO Android's UI on most current phones is already sluggish, but usable. Nokia's is just way into unusable-land. Button-press lag of over a second (sometimes several seconds) was common, and would elicit double-pressing by the user (which the OS will then happily process). Navigation of menus and other UI elements was just about completely impossible because of the slowness. How enjoyable would your computer be if every mouse click took a whole second to register, and you had no hint that the phone is actually working in the background? Couple this with an insensitive screen that would routinely miss presses in-hardware, and you can see where this is going.
- An insistence on animation on a platform that is clearly too slow for it. Apple's UI is a joy to use because of the transitions and animations that accompany many user actions. Android does this too, but the slight sluggishness makes this appear somewhat unrefined - but that's okay. The framerate I got on the Nokia apps was so slow that it became confusing if the machine is in the middle of a transition or just plain done.
The UI was also somewhat confusing - but I'm willing to let that one slide. Every platform has certain metaphors and paradigms that the user must learn, so having not used one on a day to day basis I can't really comment on whether or not the UI in fact sucks.