Gimp has a bit of a learning curve but it is well worth the effort.
Gimp is very much like Photoshop. One difference is Gimp can’t handle 16 bit images, but that would matter to few people. Also, Gimp lacks the easy automation (batch processing) tools Photoshop has and I don’t think Gimp has Actions you can make or import. Other than that, Gimp has many tools just like Photoshop.