These people who hate GIMP didn't really practice with it all that much. I use for my day job, editing photos and making content for marketplaces. It works very well.
The workflow may be different to PS, yes, but that does not make GIMP bad.
Also, for those who hate the UI, two things. First, why don't you help the dev team? And second, we'll have GTK3 support soon (finally).