Same experience as others -- if the seller is listed as backcountry.com, you're in very good hands. They have amazing customer service, and will make things right. The only thing to know when you're on geartrade is that you don't have the same warranty you would if you purchased through backcountry.com proper. However, for most gear, that's not really an issue.
I buy without hesitation when backcountry.com is the seller; if its anyone else, then I would ask at least one or two questions of the seller to see if they seemed responsive and knowledgeable. But honestly, I think I've only ever bought one thing on geatrade that wasn't from backcountry.com.