I've been playing around with Illustrator a lot more lately. I think it has a pretty steep learning curve if you started with Photoshop and then moved to Illustrator. The keyboard shortcuts are all different, and "thinking in Illustrator" is very different than Photoshop.
I want to design more things like icons, and I've done a couple of website designs in Illustrator so far. Coupled with a Wacom tablet I think Illustrator is pretty sweet.