I'd say it depends on what you really want to do.
If you just want to be able to blend/combines images and do some very basic stuff, I'd go with something else.
But if you're interested in doing more in-depth stuff, like specific coloring and such, Id' go with Photoshop.
here are some signatures and Avatars I made from the premiere of The Lorax. I think too of them I made arent that good but I will share them anyways if any of you want to use them please credit me. I hope you like them.