One thing the GIMP doesn't do (or used not to do) was handle LAYERS at all. I'm always using this feature in photoshop so I'd really miss this.
BTW I've posted previously that Adobe has considered Photoshop CS2 as "Abandonware" --It's posted serial numbers (generic) of all the CS2 suite on its website and de-activated the license / activation servers. Unless you need the new features of Photoshop such as 3-D and a few new effects CS2 is a perfectly great learning tool (also has all the layers and adjustments most users would want).
Grab it quick as I don't know how long this will stay publically available.
Incidentally -- these other OS'es are fine if you want a conventional desktop -- I quite LIKE exploring the new options though.
I haven't actually found ANYTHING I can't do on W8 that I couldn't do on W7 (apart from play Minidiscs - which I can do in an XP VM anyway) -- okay I might need to change the workflow a bit but I haven't found the OS such a pain that it would be impossible to use it on typical Non Touch laptops..
Of course everybody is different and YMMV as always.