I use BTi Free in the evenings and all weekend. (ISDN 64K).
I think its fantastic, it has been through lame periods of access, but at the moment it is very fast. I can play games with a constant 50 ping (Counter-Strike, Games-World and Jolt! servers).
Downloading is fast, and unlike other free isps, i get on first time everytime.
I also use RedHotAnt, hmmmmmm for surfing in the day. Getting on takes from 30 seconds to 5 mins in the day. But once on the speed is good, and at nights i cram it on 128.