Yes there's a fairly decent curve. Yes, it's worth it. I'd say most of the differences you're going to encounter is going to be a matter of "geography" since they generally do the same thing for most general purpose projects/needs. Click "here" instead of "there" - get it?

I'm in the same boat as Quest - I'm a keystroke junkie - saves me a truckload of time.

And speaking of saving a truckload of time, learn how to create "Actions" for repeated procedures - set their keystroke shortcuts and memorize them. You'll just get faster and faster.

CaptainJack1 - that (control wheel scroll to zoom) must be infuriating! ;-) I've got a keystroke command old habit they changed on me - which was infuriating when I purchasd CS4 - the new "Select>Modify>Feather" has been changed to Shift+F6 - used to be Crtl+Alt+F. Sounds small but when you do it multiple times for almost every image you work on (and I do a coupla hundred a month!) that's a big freakin' change for me!

And like CaptainJack1 said - you don't have to learn the "whole thing" all at once - just what you'll need to be using to tackle each project. There are entire sections of PS I've never touched (and probably never will)!

Hop this helps-
-Lew