I have used it several times, no problems. If they want unrealistic amounts, I pass. Sometimes you can catch an item with no reserve, and few people found it to bid, so you get a good deal.
In all cases, know what you are willing to pay, and know how much over that makes sense. I never bid until the end, then use auto-bidding. I never know til it ends if I got it, but I always know what I was willing to spend.