Photoshop is great, trust me. I use it everyday. And, yes, it is Mac compatible. In fact, it works better on a Mac than PC as it is more of a Mac program.
The downside is the price. You'll be dropping around $600 for a program that does way more than you will probably ever need. I work on several thousand images a year and I probably don't use a tenth of what the software is capable of doing.
On the other hand, Photoshop Elements runs under $100. Just boils down to what you think you actually need.
