It still has a few quirks, but it's mostly opinion at this point.Inkscape vs.

(Final note: despite what many people say about the GIMP's user interface, I'd take its over Photoshop's any day. If I had to choose a single tool it would be the GIMP. I don't think either is really very well-suited to web design (yet), but if I were doing my web development primarily in graphics editors, this is probably how I'd do it. I would tend to believe that in this case, a vector graphics editor like Inkscape is going to be better for quick mockups and prototyping, and the GIMP's going to be better for creating the final products. That said, if you're making images for a website you're going to end up using raster graphics in the end, and the GIMP's going to give you more fine-tuned control. If you're going to be moving things around a lot and resizing things to get them how you want them Inkscape is going to be a lot easier to work with here. Here though, Inkscape does have the advantage of being a vector graphics editor. (And there are a lot of tutorials and plugins floating around if you end up needing them.)

It's a far more mature and polished program. Right now, for anything that doesn't specifically demand vector graphics work, my general preference would be the GIMP. That said, I have used the GIMP and Inkscape a fair amount, so maybe my perspective will be helpful. I've never used Fireworks, I do as much as possible of my web design outside of a graphics editor, my tool of choice for website mockups is a whiteboard, I do the layout of my websites in raw (X)HTML/CSS, and in general I only end up using the Gimp/Inkscape for quick sketches or when I specifically need to create/modify an image.

Inkscape vs gimp designs