Ooh! I hardly ever even think about using alpha software, but I wanted to see what NNW 3 had going. Brent Simmons was so enthusiastic about his new baby that I had to see why. Really slick.
Note the right column of tiny screen shots. That is so much more fun that the typical list of tabs showing pages you have clicked on. Makes it easier to navigate too.
No problems so far. I did take his advice to backup my netnewswire folders first because I may need to go back to 2.1 if problems arise.
UPDATE: March 7. Eight days later I am happily using NNW3a and do not plan to turn back. It has crashed a couple times and misbaved once or twice, but no data was lost and I just did a force quit and restarted the app. No problem. If you enjoy NNW, you may want to try this out after backing up a couple files that you will be advised to backup.
I also use Google Reader sometimes. But, since moving up to NNW3, I have been using NNW more and GR less.