Mind you, I have also seen the original FMA (2003) but It sucked after the first half. Although, it was more dark and emotional than FMAB, I still think FMAB is better! FMAB did more justice to the characters and plot than the original. I don't remember liking any characters except Edward and Hughes. Honestly, It was quite forgettable, well, except for the main theme music.
As for the flaws, the first few episodes are fast-paced but only people who have seen the original version will notice this. Another issue people can have with FMAB is its humor which seems out of place in some scenes.
I'm not saying its the best anime ever cuz it has its flaws. A lot of fans of previous adaptation don't give it a chance and recommend others not to watch it. Don't listen to them and go watch this anime. Even if you don't like shounen (like me), you will definitely like it if you watch it with open mind n without prejudice. I promise you won't regret it!
