Gimp has a learning curve just like everything else. It's _different_ from Photoshop, but for most tasks it's not actually _worse_. It needs to be learned. I learned it and it's comfortable to use.
Does Gimp have any kind of smart object equivalent yet? I've been using Photoshop for years and haven't been able to move to Gimp because it's missing a lot of "non-destructive" editing features like smart objects, smart filters, adjustment layers, etc.
Not that I'm aware of. The workflow would be to make a copy of the thing before you do a destructive operation on it. You can put it in a hidden layer or something.