I suppose some of them are a bit gimmicky but never the less, some of them do a great job and for lots of tasks are more than enough. Photoshop is, I guess, the difference between driving to work and winning in Formula One. Really depends on what oyu want to achieve and how far you are willing to go to do it.

what are clipping masks

I remember asking chasingdemons the same question, last year. Clipping masks are magic. They let you blend layers together in a whole other way. Here is a fairly simple tutorial that explains some of their power.

http://www.photoshopessentials.com/basics/clipping-masks-essentials/ ;D