I'm not saying it's bad by any means. Just a tad overrated. I mean, there were some brilliant characters like Johan, Eva or Runge, but aside from them, most were just bland good guys or bad guys. Even Tenma felt somewhat boring at times, with his heroic aura and politically-correct moral principles. And considering this character appears in almost every one of the 74 episodes of the show, he develops surprisingly little. Adding this to the unnecessary drama and tear-jerking episodes, and this becomes a flawed masterpiece at its best.
The truth is I expected much more moral ambiguity and thought-provoking material from "Monster". But hey, this is just my opinion.
tl;dr anime: some like it, some don't