"done" is defined by the creator of the software. If you're the creator of GIMP and it's suitable to your purposes, you can call it "done". But ostensibly, you made it free so that others could benefit from your efforts, and possibly even open-sourced it so that it would be accepted as safe to use. If that's the case, then something isn't "done" unless you're happy with the number of users who find it acceptable.

I suspect that the creators of GIMP fall farther on the side of "suitable for our purposes" than on the side of "suitable for a large number of people's purposes" (however this may be unintentional and/or laziness or bad strategy on their part).

> Actually check it out yourself, and give yourself some time to get used to it.

Assuming I haven't is an extremely bizarre but inexplicably commonly-made mistake. Can you explain what leads to this mistake?

> If you care about not using PS of course.

You might not realize it, but this is a (perhaps unconscious) "no true Scottsman" fallacy. I take it you're not a creator of GIMP, so you don't have any authority to say what GIMP is intended for. So the idea that it's for people who "care about not using Photoshop" isn't a valid assertion. That's your opinion, but you should try to back it up with something. I see nothing on the website or the Wikipedia page that backs up the claim that it's for people who "care about not using Photoshop". It seems like it's for a much, much wider variety of people than that. Why gatekeep like that?