Very good, but maybe lacking in polish.
Blosics is a very fun experience, and while it does use a system that is, well, over-used (physics-based gameplay in a flash game? I've never seen that before. :P), it's still a fun game. The game could have made a ten for me if it had a little polish, as there were quite a few glitches, like: http://img39.imageshack.us/img39/8176 /pinglash.jpg.
TLDR: It's a very fun game, if lacking a bit of polish.