I'm not sure Gimp was ever especially good. At one point I suppose they matched up alright with Photoshop and was pretty much the only alternative that didn't outright suck.

These days though there's a lot more options to choose from that are generally pretty good.

I don't think Gimp was ever very good, it just happened to be one of the first open-source alternatives that didn't suck outright. These days there's a lot more options to choose from that are generally pretty good.