Boomkins are fun.
And are getting some nice toys in Cataclysm.

The main knocks are:
a) harder to manage eclipse mechanic, vs other classes dps systems.
b) cannot heal, in their dps form.

The team has superb AoE, probably the best.
And with stealth, you can pick and choose many of your battles.
With Cat Form/Sprint and Travel Form, you can run away from a lot of lost battles.

With Flight and Aquatic forms, the PvE aspect of leveling up is easier too.