I've heard TRX was developed for the Navy SEALs so they could exercise anywhere when deployed. I think it's awesome -- definitely the funnest, most effective exercise equipment I've ever used. I definitely want one for Christmas.
If you check Amazon.com you'll discover dozens of knockoffs for half or one-third the price. I really can't offer you any kind of review, but I'm sure they work fine.
If you've never seen suspension workouts in action, watch these videos: