Multi-threaded, Pen Tablet support, Handles large images well, Decent RAW image conversion via UFRaw, Multiple undos with visual history, Accurate Heal tool, Near-flawless PDF and vector rasterizing, Color profile rendering and tagging, Top-notch noise...
Slow large brush feedback, Lacks 16- and 32-bit per channel RGB, CMYK color support, Web slicing needs work, Pixel-based brushes are a pain to deal with, Getting a plug-in installed is still a Unix-admin thing, Masked layers dont update while being tr...
Obviously, this review doesnt cover everything that you would want to do with an image editor, but I think it covers a broad range of common hobbyist and professional tasks. Its more of an audit of the features and tools than a rundown of everything ...