Last year I tried the Resharper 3 plugin for Visual Studio, and posted my thoughts on it:
http://basternae.org/blog/2007/07/26/jetbrains-resharper/
It was OK, but not all that special. It had potential, but wasn’t quite “there” yet.
I just finished trying out Resharper 4.0 and you could paste the Resharper 3.0 review in its place. It’s neat, but not so neat that it’s a ‘must have’ utility. The features added in the latest version really aren’t anything I find useful — I don’t refactor Visual Basic, don’t use LINQ, etc.
It does, however, appear to run a little faster than version 3. That might just be the system I’m using it with, but the slowness is no longer an annoyance.
I’ll keep my eye on it. Maybe they’ll add something I can’t live without in a later version.