I've also used gimp for approximately 8 years and it has made HUGE strides in the past few years. In fact, I've done a few professional, or semi-professional (ie: not paid) photo restoration jobs recently and I used gimp to do it. Not that surprisingly, people still absolutely loved the work I did restoring pictures of their loved ones or whatnot.
Photoshop still has nothing equivalent to the SIOX background removal tool as the guy who wrote his PHD thesis on it wrote a gimp plugin. If you've not seen it, it is kind of amazing: http://www.siox.org. See this video for an example using a much much older version of gimp: http://www.siox.org/videos/siox-in-gimp.mpg
Think about a new graphics design person coming to photoshop. It is very much a learning curve, a higher one than gimp.
I did buy both of them a long time ago and used them for many years on an old Mac.