The project is very active and Charlie is quite responsive to bug fixes and feature requests. I have recently reported two bugs in one discussion and two feature requests (1, 2). Charlie was able to quickly apply the patch for one bug and implemented the instance of exception assert feature right before 2.5.2 release.
I have heard some good stories of MbUnit as well, it's a mixed feeling to see two open source test framework competing each other. Wouldn't it be nice if they can work together instead of reinventing wheels twice? The combined effort could have produced much more complete test system...
