Simplest thing in the world to me- find a user, look at their friends page, pick anyone interesting to friend, look at *their* friends page, and so on. Whereas tumblr always seemed to be happening somewhere else, with any single entry followed by a useless list of people who reblogged that entry without any sign of further comments at all.
Which said, I did find some good tumblr RoL commenters whose posts were interesting, even if there seemed no way to join in the discussion. Hope they come over here.