When you think what a really good job the DCAU did with Superman/Batman it seems a real shame they didn't simply take the script from "World's Finest" and shoot it live action.
(World's Finest -- the 3 episode meeting of Superman and Batman in "Superman: the Animated Series")
I mean, I had small issues with the Bruce/Lois romance element, but it was still a terrific story.
I really like the Timmverse in general, but I don't think you can just lift it into movies. You can get away with things in animation you can't in live action: the Joker in particular pulls stunts that I think would come across as more goofy than intended in live action. And the stories are paced a lot differently than I think you can get away with. The entire run time of the entire World's Finest arc is probably barely over an hour without commercials.
World's Finest also doesn't happen in a vacuum. It happens after three years of animated Batman and then over a year of animated Superman. We already knew both characters - specifically these iterations of those characters - before they meet. DCAU had the patience to develop both characters before putting them (and their rogues gallery) together. I think that's important here, was important to Avengers, and is probably something missing from BvS.
I like the DCAU a lot. In many ways, it is not only my favorite iteration of the DC universe but also the definitive touchstone I reach for when thinking about these characters. But I also think that the tone, characterizations, writing, and medium itself fit together well in the DCAU in a way that makes it all work, but won't necessarily work everywhere. And I think it should also remind us why we should try to keep an open mind when others try to do something new. Its not that it will all work, but the possibility of failure is necessary to create the opportunity for great things to happen like the DCAU. You can nitpick the DCAU: Batman's ears are ridiculously large, Lois Lane is too young, Clark is a little too wisecracky, whatever. Its not perfect. But it works. People nit pick Nolan's version of Batman, but it works. I think Man of Steel is far weaker than either of those, and it seems anyone who owns a pen or keyboard isn't too crazy about BvS at the moment. But I think if MoS and BvS ultimately don't work, that doesn't mean we look backward to fix it, we should be handing it to someone who will come up with something new. Nolan's Batman is nothing like Schumacher's or Burton's Batman, who was nothing like the Adam West Batman. The comics have at least a dozen different iterations of Batman. We have the DCAU Batman already. We should be looking for the next one.