Zack Zoll , Mar 03, 2013; 05:20 p.m.
I have Gimp on my netbook. It works okay for making minor changes to already compressed files. As others have said, it is terrible for RAW files. I believe it just got 16 bit support, too ... or maybe they're working on it right now. One of those.
But it cannot be overstated how terrible the user interface is. It's so bad that I think it must have been intentional - making commands and pathways as different from Photoshop as possible to avoid lawsuits and C&D orders. Oh, and I've never used a non-Adobe editing program with better print drivers than Photoshop. I've used programs made specifically for printing that were better, but never an editing program that was better.
Also, if you, a friend, or a family member have a student ID, you can order Photoshop online for something like $180. I don't think it's worth $550 to save some hassle over using GIMP/etc., but it's well worth $180.