An extremely good interface for editing and retouching photographs
Okay for doing painting and bitmap art creation
Mediocre for doing graphic design -- alignment and layout are frustrating
Abysmal for doing web design that isn't brochure-like
Omnigraffle is a terrific example of a general graphic design app that is suitable for web design.
I agree (as much as I can without actually being a designer), and I think a lot of people have lamented the loss of Fireworks when Adobe gobbled up Macromedia. It's also worth mentioning that Inkscape is a good tool if you're on Linux or Windows.
That said, regardless of how mediocre or abysmal Photoshop might be for graphic/web design, it's what most people seem to be using for it these days.
