Quite umderwhelmed to be honest. From a pure user perspective 1.2 only brings two updates to the table.
Maps are improved (but not as good as competition) or Nokias own symbian.
Skype video call - a feature that really should have been there at launch (AFAIK ff camera was not usable with anything before 1.2).

I personally don't feel any speed or power improvements. Fx media player still stutters plenty when using BT headset + recording GPS (ecoach).

All the horizontal views are for show only, as none can be used in that mode (can't write location in browser, write mail or sms/conversation).

To me, the only improvements are minor (shift arrows in browser to goto top/bottom of page and press hold to get alt symbols on keys).

The time spent on 1.2 really worries me for the future of Nokia software. Don't get me wrong, I love my N900, but with this update speed, it will fall behind and won't win over new users.
/rant off