The metal teeth are fine, and in fact fit perfectly. Someone like him would be loosing many teeth in both fights with Batman and prison beatings (in which he would just take it and be laughing all the while). Actually one of the things that bugged me about comics through the years, everyone is getting their teeth knocked out yet are walking around with perfect pearly whites in every panel
those tattoos on the other hand...tattoos are fine, but those tats look like something some one trying to replicate / pay tribute to the joker would get (like a fanboy or lackey/goon).
I do however understand the direction. Each cinematic Joker took great care to distance themselves, personality wise, from the previous version, and this looks to do that perfectly thus far. i'm optimistic about it.