I've used photoshop on a contracting (professionally) basis since I was 15 using version 4. I've used just about every version since, but kind of stopped since Adobe is moving to more of a service based model with the creative suite cloud crap.
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
Maybe it's because I'm a software developer myself but I never had a problem with GIMPs UI. I never had a problem with Blenders UI either (only when they changed some things and I couldn't find them anymore because they are now somewhere else). In fact back in 2001 when I once tried Photoshop I found GIMP quicker to grasp than Photoshop (maybe because it has less features and thus one can get an overview of all the functions quicker).
Having used both, I think that gimp is actually much easier than Photoshop. To prevent him from sending me 5Mb pictures over email, I showed my father how to shrink the size of pictures using both gimp and photoshop. Then I asked which he wanted to use and he went with gimp, which surprised me. But using it more, the menus do make a lot more sense in gimp than they do in photoshop.
Think about a new graphics design person coming to photoshop. It is very much a learning curve, a higher one than gimp.
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