When I started this design stuff, Freehand 7 was the top-of-the-line program to use. Illustrator wasn't quite as user-friendly as Freehand... at least, the drawing tools were alot easier to use in Freehand. But since Freehand was slowly going into the crapper, I picked up Illustrator and gave it a try. Wow, is all I can say. This program has evolved tremendously. It's drawing tools are intuitive and easy to modify. The output from Illustrator is by far more universal, which is important when sharing artwork or printing.
The new 3D tools are simply amazing (I have yet to find a need for them, but I want to). One of the most usefull parts of Illustrator, for me at least, is the pixel preview. Drawing with vector tools in a raster environment is my preferred way of desiging screen graphics, and it works great in Illustrator (similar to how well Fireworks does it).
TipsMake web graphics in Illustrator
Who knew five years ago web designers would be making @2x sized graphics for high resolution displays? For any vector web graphics already created, it's simple to export a retinia display sized version of the same graphic from Illustrator. Of course, same can be done with vector graphics in Fireworks.