Summed up my thoughts 100%It thought it was pretty good. Fantastic performance by Joaquin Phoenix (he truly owned the screen) and some pretty good twists working it in with the Batman lore (loved the Zorro Easter egg).
Phoenix was definitely believable bridging the character from being mentally ill to homicidal -- when he recognizes the euphoria he receives from committing murder it provides a contrast to his earlier meeting with the shrink when he spoke of only having dark thoughts, like he recognizes a breakthrough in how to achieve personal happiness. I found it completely believable that this character could go on to become a cold blooded, maniacal mass murderer.
What I'm not sure about is whether this interpretation could go on to become a criminal mastermind. As well as they did depicting the development of his fetish for homicide, I don't think they illustrated any repressed brilliance within that would allow him to commit organized and developed criminal capers. Assuming this was just a one shot I guess we won't get to see how this Joker would cross that bridge.
Is it possible that the meds were holding him back?I watched this last night. As someone who is really not invested in the whole universe of these.characters, I really enjoyed it. That said, I can see the criticism that it is hard to imagine this character being capable of orchestrating any sort of genius planning.