I actually really like the concept of T61, and I enjoyed it a lot at first, but the site is quite buggy and difficult to use at times and I don't like the interface much. It is also really hard to connect and track other users or artists, or to have much control over what you listen to. The result is that you end up stuck with maybe 5 different playlists you have to listen to in the same order.
It is really great though if you like the game aspect of it - you can discover a lot of new music easily and earn points doing it. Great source of procrastination.