Illustrator learning curve?

Yes. Huge difference at a conceptual level, which the similarity of the interfaces disguises somewhat. Once you get right down to it, though, it's really this simple: Illustrator is about creating artwork with objects, not pixels, and InDesign is about creating layouts by putting stuff in boxes.

Everything else is just detail. However, I've been at this game for nearly twenty years, have used nearly every version of PS since 1.0; AI since 5.5 and ID since 2.0 and I still find out stuff on a weekly basis that I didn't know!

Cheers

Jim

 

If you're familiar with Photoshop bezier curve tool, that helped me a lot when I was starting out with Illustrator, since I use the pen tool frequently.

Like Jim said, they're vastly different programs, but I don't think it's too hard to move from one to the other.