I'm a Twitter power user so in theory this is the kind of thing I would like. (And I did upvote.) But I think you need a value proposition to get people to use the site that isn't just reading reviews, because most usernames I search at the moment will not have associated reviews. With a clear alternate value prop, you'll have time to build up the number of reviews and then do something interesting with them, like "most-recommended accounts for [topic]" or whatever.

Anyway, I do like the idea of Yelp-meets-LinkedIn layered on top of Twitter.