Well, they recently had some delays with Dwolla withdraws (Dwolla's fault), and tradehill has lower fees.  Competition is good, it will lower transaction fees, increase features, and make markets actually compete for your business.

Why do you think EA sports basically releases a roster update every year for Madden football?  No competition.  They don't have to compete for your business, if you want to play video game football, you only have 1 choice.