ET3D: I wish you good luck using GIMP. If it's enough for you, that's great.
With GIMP you can do (almost) everything you can do with commercial software, so it should be enough for at least 95% of users. I have been forced to use GIMP sometimes for educational purposes, so I am more familiar with it than I ever wanted to be.
The biggest problem is that GIMP is a real pain in the a** to use. Often it doesn't seem to have any internal logic, except for backwards logic, if one menu works one way, the other menu is sure to work just the opposite way.
And when they seem to have corrected something (adding the long-awaited one window mode), they do something absolutely f***ed up next, like dividing the old "Save" and "Save as" so that "save" is now more or less a workspace save, and you need use "export" to save as jpg, png, gif, etc.
If I had big problems adjusting to this, those poor souls who are maybe using image editors for the first time ever are completely lost with this "innovation".
And then there's the issue of having to restart the program to reset some tools, which may or may not reset when restarting. And so on.
Still, having said all that, I have a commercial image editor only on my desktop PC, for my two laptops I have installed GIMP, and actually get everything done with it. But as with most free software (unfortunately), they haven't really spent too much time thinking about usability and user-friendliness.