The anime, if you watch it before the manga, is likely quite good. The people I know that watched the anime seemed to enjoy it, though they agree that the manga is superior. Though, the general opinion seems to be that if you read the manga first, the anime won't seem very good. Main problems with the anime are pretty much anything that wasn't in the manga. Some of the filler is extremely stupid, as are pretty much all of the anime-only ideas.
The manga is pretty good. The story moves on at a decent pace, though it takes a short time to get to the main story, choosing to focus on random adventures and experiences to better acquaint the reader with the characters, which isn't necessarily a bad thing. Currently, the manga seems to have recently reached its climax, and is heading towards a conclusion. The character development and tone of the manga is more believable and has less of a shonen feel than the anime's.
So, if you want to bother with the anime, watch it first. If you don't like it early on, chances are you won't like the anime at all. It takes it a short time to pick up, but it's decent. Or as I did, start the manga first and once you catch up watch the anime and see the differences.
tl;dr FMA anime 7/10, manga 9/10