I did consider Nexus1 or Desire before getting N900.

But it couldn't play xvid files or various other codec combos.
Also, hardware keyboard was a priority. Can't stand just touch.

It's been only around 6 months since N900 became available.
I'm very happy with what the community was able to create so far.
Once PR1.2 comes out, I'm sure N900 will be pretty well rounded.

But everyone has different needs. So I guess Desire is better in its own ways.