After seeing a few posts i began to wonder why people keeps putting gimp outside the frame, what are the professional things that make people stick to photoshop (well aside the floating windows, and the 20 years of photoshop experience)
Diferences so far (well actually lacks)
* no CMYK, LAB, Pantone and Hexachrome native profile
* color depth is 8-bit at current version 2.6.10.
* Adjustment layers
* Lock Layers they promised it at 2.8
* Layer comps
* Patch tool
* A free transform tool (A merged one, they exist but at separated tools e.g: rotate, scale; )
* Clipping mask layer
* Editable vector supporting layer masks and effects for working only in gimp
* Advanced character settings and writing on curved paths that remain editable also missing but this belong more to a vector program.
* Conversion of font elements (Convert text to path) into shapes with subsequent editing
* Maybe too much to ask but no Content-Aware Scale, quick selection tool, Smart objects