FMA '03 being a more thoughtful and introspective character based series compared to Brotherhood is all well and good in theory. Then you get to the actual character writing itself, which is horrible. Instead of anything that's actually interesting, there's nothing but ton after ton of obnoxious angst with zero thought put into it, all while the show tried to pretend that it's "deep." Brotherhood spends less time on development of its characters, but it does way more with the time it does have, and packs all the characters with lots of heart. '03 feels really soulless by comparison.
I intend to do a full rewatch of 2003 before making a detailed defense of it, but my memories of Brotherhood are clear enough to say that I definitely found it to be soulless in the end. It's hard to say it does well with the time it has when basically the last 12 or so episodes are one big dragged-out finale arc in which barely anything meaningful happens. I found that whole arc pretty silly as well, but it is a sort of cliche battle shounen silliness so it probably doesn't bother people who are big fans of the genre. The only parts of Brotherhood which I feel positive about are the good action animation, some of the OP/EDs, and Olivier Armstrong.