For buyers, it's great. For sellers, it's pretty shady.
The charge 12 percent on all purchases for their commission, and hold shipping charges in escrow until they decide you can have it back.
All of their business practices are tucked into the fine print in the Terms and Conditions of their site, and rather hard to find.
Moreover, once you sell something, they reserve the right to take up to 5.5 weeks to pay you, with no guarantee they ever will actually pay you. So if the seller gets some sort of buyer's remorse, you get treated like a criminal, the seller gets his money back, but there's no guarantee you get your gear back. And you get to leave the commission with GearTrade.
Turns into a shitty deal fast.
Also, they dress all of this up as if they did some sort of work on each individual transaction. In reality, what sellers have to do is surrender all control and credibility to one guy who built a website, who will pay you if he feels like it.
It was your gear. You took the photos. You wrote the ad. You packaged and shipped the gear. You printed the invoice on your printer with your paper and toner. You did the majority of the work in this transaction.
GearTrade just made ghetto check-cashing store fees on your work.
So, if you sell anything:
1. Hope you don't actually want/need the money
2. Be prepared to wait for more than a month to get paid
3. Be prepared to get screwed royally if the buyer gets cold feet
4. Expect absolutely no support from the site's lone administrator.
5. Enjoy Geartrade taking their share, and you getting paid absolutely last, if at all.
Craigslist wins every time.