"No decent OpenType typography, no layer styles, no smart objects, no dice." (from the comments on the OP)
If all I need to do is crop or scale an image than sure, I might get by with gIMP though in that case I'd arguably get by better with something simpler than gIMP.
But, I actually use vector layers with layer styles ALL THE TIME. I actually use text layers with layer styles ALL THE TIME. I actually use non destructive adjustment layers ALL THE TIME.
Photoshop layer styles are like CSS. You can declare your styles and then edit vectors or text and the styles apply dynamically.
AFAIK gIMP has no equivalents. Those are not minor features. They're what set Photoshop apart.