I haven't touched Photoshop since like CS2 I think, so really can't compare the two, but I will say that GIMP 3 was a huge enancenent to GIMP. It now has non-destructive editing. For my common uses, this is giant. Not having to redo 8 steps because I decided step 1 wasn't right is so nice.
Of course Photoshop has done that for ages. My only point was that previous perceptions might be a little dated. And with the 3 update came with huge backend changes that will hopefully accelerate other feature development. Of course I'm sell on hope, but I'm excited for the future of GIMP. Also, now that 3 is out, they have been hinting that that are open to talk about a name change, which I think would be healthy if they want increased usage.
We're a little behind schedule.