I have been using this since before the 1.0 days and it has always been my favorite BT client. They have fixed so many of the issues that plagued it and have made it even better.
Love the new options like ability to pick which files to download and their rank, also encryption and IP blocking is nice. It is very light weight and has everything you need, not to mention it looks great too.

If you need a BT client on the Mac, look no farther Transmission is the best.