I have been reading Fullmetal Alchemist for a long time, and I love it! There's nothing that will change my opinion towards the manga, there's no flaw! It really isn't the same trite kind of shounen manga at all. (For example, no offense to Bleach fans out there, but as much as I love Bleach, the story just got really...boring)
Although the art didn't appeal to me in the beginning, I now feel that it's drawn with confidence. The lines are bold, and I don't see those kind of lines drawn. Every character is special, as I have noticed almost everyone's eyes are different. Especially Ed's, he has those determined eyes that look that they'll never falter for even a second. He's also very special because of his braid. >< The chimeras are also very well drawn, as well as all the little details of the automail, which probably are a hassle to draw.
Putting that aside, the plot is phenomenal. In the beginning, I was only reading the manga for the entertainment and the idea of alchemy, and for Ed and Al. But as I kept reading on and on, I realized that there's so much more than just the fun and laughter, the tears and sadness of the story. Rather, Arakawa has took the military and scientists together and mixes it with the government. It shows conspiracies within, and it makes me think that our world is probably like that. We're all oblivious to these things, living our daily lives. Also, the deep bond between two brothers, they live for each other, and I wish I was like that with my own sibling. There is also the relationship between children and adults. Ed and Al never really rely on anyone else, but there are people like Mustang who would like to be relied on. Children are still children-they shouldn't grow up too fast. Arakawa also incorporates "God" into the story beautifully. The idea that with alchemy, even with that type of power, you would be condemned for trying to revive someone, that no one can get so close to God.
The concept I like the best is that all the bad guys are named after the 7 Deadly Sins. It shows that humans aren't perfect and those are the most hideous traits that we all have.
My favorite part of this series is that the everything is unique. The protagonists aren't like all the overused concepts of the shounen protagonist. The Elric Brothers may be prodigies, but they're not constantly popping out new powers or having powers that are surprising to everyone else. They're intelligent young boys, and what their logic and ways of fighting are what someone would expect from prodigies, so it's not surprising. They're not trying to be the best, nor are they the best. They're not invincible nor perfect.
Lastly, I just love all the characters. Ed is so...well there's no word to describe him! He's just awesome. He's funny, determined, and I hate seeing his sad face. He's unique, especially the part where he hates being called short! Al is so cute too! He's very kind. That reminds me, I love how Ed may not seem like the nicest person, being rude all the time, but he's also just as kind as Al inside.
Anyways, all characters in the story are essential, and like someone else said, they aren't just thrown away after being drawn for an arc. the story is just a big masterpiece.
Hmm...it seems like I've over-commented on this...-__- Sorry! I'm pretty sure no ones gonna read this though...><
BUT I HIGHLY RECOMMEND FMA!!! PLEASE READ IT!
By the way, the anime is really good too! The first 51 episodes has its own story, which is really interesting. The OVA is awesome too! Brotherhood goes more according to the manga, but I think the anime is worth watching.