TY Dunno. It was quite hard first (didn't understand anyhing), but I learned it about...2-3 days of exercising? (gosh, how I write that :S )
There is still neat lil' tricks to find out for me too. I'm not guru with GIMP. (I've never used that page before, so I can only hope that is good) But is is quite addicting when you really learn to use it. Photoshop is good too, but I prefer GIMP.
Off-Topic: f you want to remove red eyes from some picture though, Photoshop is better.