Well... I just finished this manga and decided to write a comment. Mostly just to state my experiences with "Fullmetal alchemist" ^^
You think the beginning is just the usual and the characters showing up won't be of any use anymore - scratch that, not even the chimera-girl in the beginning was forgotten. This is quite unusual and to be honest, I love it. Every character has its own role - and is absolutely needed. And furthermore: They aren't just forgotten when their arc is over. In some way they resurface - and that's the fun part. It makes the whole story complete and adds to its plot.
Needless to say, the characters are freaking loveable. That's a bit unusual for me to say nowadays about characters in a shounen manga, but hey, what can you do? It could maybe be due to the hilarious espressions and actions of them, because of their personalities and their fights. But you should just check it out for yourselves - you'll most likely like our little, easily irritatable alchemist-kid Ed, the big sweet cat-loving and slightly naive amor Al, the date-and-woman-loving Roy Mustang with his over-serious gun-fighting sitter Riza, the feared-by-all-housewife and her hubby and and and. But heck, that alone can't describe those charas. Check out the manga for that!
But it's not the characters or the art style - it's quite nice by the way and it gets better the longer it goes on (and there's (character) growth visible) - that makes FMA what it is today: It's the plot.
It's slightly surprising. At the beginning it was hard for me to get into FMA, but the longer it went on, and especially when I past the point where the old anime finished, I got hooked. I loved the anime before - but for some reason I still had a problem to continue reading the manga since many elements were familiar and maybe because I thought some other elements would be similar as well.
Haha, I should have known better. Stupid me, all that was similar was the beginning. It went on a different turn then and took me along with it ^^ I got hooked. And finished the manga quite fast as well. To tell the truth, I really enjoyed FMA. And of course, why not? FMA knows how to be convincing with a clear, pretty art style, also great characters and an amazing plot.
I would just like to leave a last note: Even if you aren't convinced by this manga at the beginning, keep on reading. Things change. The characters grow up, you can see them mature and this also in an visible way. Things you may hated at first could change - but if you just hate the characters and wish them all death, it may be better to cease reading.
But honestly, if you aren't exactly obsessed with a genre not listed up there, you should just give FMA a try. Who knows, maybe it will become you new favourite manga? At least it has the potential!