It probably depends extremely on what your needs and interests are. My wife has a N97 and I find it terrible - absolutely impossible to use, some handicapped Frankenstein IMHO (I come from a N82). The N900 OTOH makes me happy each moment I hold it in my hands, because it literally vibrates with it enormous potential.
Maemo will catch up very fast - just watch this place and feel the acceleration going on since devices began to roll out a few weeks ago. Now let Nokia add a firmware update or two (and fix that shameful Ovi Maps app), then we will really get going :-)

And yes: classic 3G calls are not (yet?) it's strength :-)