This new version is pretty cool! I hadn't tried the first beta or alpha releases.
The new gradient tool is pretty fun to try out. I might use it to make some impress back grounds since star/open office is missing this feature.

http://fileforum.betanews.com/detail/PaintNET/1096481993/3

is it still slow as hell?

No it seems pretty snappy on my system.(just as fast as 2. whatever I was using)

I liked Paint.net to start with, nice and easy to use, but limited.
Then I found the gimp and never looked back. What's event better there's a portable version so it's not even installed.
I really hope paint.net keeps growing and getting better. I might jump back to it one day.

I have to point it out that gimp stands as a photoshop opensource alternative which paint.net does not. although paint.net is decent enough to be a complete replacement of ms paint:)

ps. compare with ps, gimp is still way behind especially when handling some huge images, and there's no position for paint.net between them.