He is my favorite live-action Batman to date. There are things I think Keaton may have done better, but Bale just nails the character in his modern form. You really get to feel for this guy in BB and root for him at all times. You get inn his head and understand him far better than in any Batman movie before and most comics for that matter.
In TDK I think he just nailed the persona of Batman much more. While he was great at in BB, especially when he is having confrontations with either Scarecrow or Ra's Al Ghul, in TDK he is just so firmly fit into this character. It isn't "ah, it is nice to see they worked or incorporated that angle in" or "I like how Bale did that," but it simply is Batman on screen. He is Batman and doing what I think Batman should do.
I know some wish he was more of Miller's dark knight and given these are his first two years as Batman he can come off somewhat naive or more fallible than comic readers are used to sometimes. But to me that is just a plus. Seeing a struggling Batman who does second guess himself and doesn't always know how best to do something or being always the utmost effective just makes him more human and interesting. Sure Bruce never came that close to quitting, but in fanboy favorite MOP he almost gives up Batman before the dream ever starts and he toys with the idea in both Batman (1989), but rejects it and again in Batman Returns where Selina rejects him for the same reasons he rejected Vicky. So I'm all for this aspect as you have four film adaptations that have probably toyed with it more than the comics and each in a unique and interesting way. And for the record, I thought it was best handled in The Dark Knight (followed closely by Batman Returns).
My only real complaints are the voice, which is a major plus to Keaton. But he is so immersed and inhabited into this role that I just kind of accept the voice even if when I first heard it, it made me chuckle. The whole performance by Bale sells it. The other is while I'm glad Bruce Wayne is more of an airheaded socalite in this as opposed to his reclusive self in the Burton movies, I did like how Keaton's Bruce (like in TAS, for example) was straight forward, take-no-**** kind of a businessman and when it came to maintaing Bruce Wayne's name. In the Nolan movies he leaves all that to Fox and comes off as a complete tool.
Oh well, I still think it is a great performance that helped carry Batman Begins to be as great as it was, because really that movie rested on his shoulders and he was as good as Echart, Oldman and even Ledger. But as usual Joker overshadows all other characters and performers for the mainstream, though.
) and I wish we'd see more of it. The private Bruce is also done pretty satisfactory, albeit slightly boring in my eyes. Keaton had less to work with and still managed to come off as mysterious and interesting. 
