I fail to understand why people hate gimp so much.

Because they’ve spent years learning Photoshop’s unintuitive interface rather than GIMP’s unintuitive interface. I learned them both more or less in parallel and found them both equally awful. (So who does have an intuitive interface? Paint Shop Pro, back in the days that JASC owned it, came the closest of any piece of raster image editing software I’ve ever used.)

In all fairness, there are a few features that Photoshop has and GIMP doesn’t, but the ones I’m aware of are professional level stuff (spot colour support and some complex editing constructs), and there’s usually a way to do without them or compensate with some other program.