I think RateYourMusic also allows for commenting pretty much on everything (and it also extends to film and, IIRC, videogames).

It might not be as friendly as last.fm on the surface, but it is surely richer in content, and more diverse. It's a gem, and I hope Sonemnic (?) doesn't drive it to the ground.

For me it doesn't really compare: with Last.FM all I've gotta do is navigate to my profile and the song I'm _currently_ playing on Spotify is right at the top, I just click it and boom, I'm on the track's page.

Besides, you can't leave comments under specific tracks on RYM.