Actually, four out of the five members are black. The guitarists (the Coyle brothers) are as well.
Musically, they've been influenced by Slayer, At The Gates, and Hatebreed. Where as bands like Hatebreed are metal influenced hardcore, GF is hardcore influenced metal.
I've seen them almost a half dozen times over the years and they never dissappoint. Their pits are brutal (well, the one's I've been to here in Jersey, their home state), because you get those idiot hardcore kids who are kicking and swinging all over the place and then your usual Morbid Angel fans who just like to push and if you piss them off, they get physical in a hurray.
If you can, try to talk to them after the show. Everyone in the band is mad cool, very knowledgable about the scene, and they deserve the best of luck. You'll propably see their singer, Byron wandering around. He usually spends most of his time in the crowd, enjoying the show.