Gimp Vs Photoshop

Hey guys im just wondering how gimp compares to Photoshop?
I've been a photoshop kind of guy since i was in junior highschool and its the first time i've even heard of gimp. When I was in JHS my friend used to create these cool images with even cooler effects using photoshop. So he got the program for me (not gonna say how) and I tried it out and it was SO hard to use. I had no idea what i was doing.
Then he gave me some lessons. The basics. And he also told me about a bunch of online tutorials that were available via search engines. this was back when broadband wasnt very fast and google wasnt the primary search engine. anyways after you get the hang of photoshop it gets much easier.
So is it worth checking out the gimp program or should I just stick with photoshop. Only reason I ask is because its been quite a while since i have actively used photoshop and i tend to forget how to use the program efficiently.