I've never come across anything free or not that beats the power of photoshop (maybe corel but that's not free). But there's nothing free that I know of that even comes close. There are ways to use it for free but not legally.
Well, gimpshop is a mod for GIMP that arranges the stuff so it is as close to Photoshop as it can get. You may have already known about that though. I honestly think GIMP will be pretty good, depending on what you want to do with it.