Nick,
Welcome to FlyerTalk.
I have been using Bing Rewards since it started last Fall. So far, overall, I have been pleased with the search tool itself, ease of earning points, and quick deposit of AA miles into my AAdvantage account (much quicker than the ridiculous 2+ months it takes for Club Bing mileage redemptions to post).
I would hope that as time goes on, the airline mileage rewards options would increase - both as to more airlines, and larger miles chunks.
All together though, I think you guys have done a pretty good job on this one!