Benefits of ImageReady over PS

I was just wondering what the advantages are of using ImageReady to slice up an image rather then Photoshop? They both have the option, and I never really bothered to go into ImageReady until recently.. And maybe give me a few pointers to try out in ImageReady?

You have more precise control over the process, you can choose alpha channels to optimise certain areas above others, the list goes on. Without wishing to be rude or put you off, you could do a lot worse than use Photoshop's own help system (F1) and maybe a Google search on Imageready tutorials combined with a look on Adobe's own site for any tutorials or resources that they may offer.

Rollovers, Imagemaps are 2 options in IR that are not in PS. * also animated GIFs