If you don't know anything about it, I would definitely suggest trying it out first because it is extremely expensive. Find a friend or a school that has it and try it out. Also, I think you can install a free trial version to try out.

It is very powerful and a great program, but also a rip off. I hope this helps.

photoshop is the best ... it has more features than most people can master in a lifetime ..

Photoshop is the professional standard for photograph manipulation, and can be sufficiently used as a platform for digital artists and painters. Here is an example of a digital painting completed entirely in Photoshop.
http://novacapture.deviantart.com/art/Keyhole-64636866

Whether to shell out the cash depends on the level of your needs. If you want to see what the software is capable of, go to Google, enter "photoshop," and select the Video tab at the top of the page. You'll get to see all the wonders of this program.

To get a better answer, please be specific in terms of what you plan to be using it for.