Not too fast, though. I think I went a bit two fast in my last Batman film, it was hard to see what was going on.
For action scenes, I'm a pretty good person to ask, as I've done a lot of them, some in more large-scale films.
One of the first things I like to do is get in the spirit with a few good brickfilm fights such as these:
The Profession
The Force Unleashed
Possessed
(Enter Vladimir Vango)
The last of those being one of my own. I like to remember my coolest fight scene, and bring myself back to that time when I animated that, trying to improve upon my methods, and remind myself that I've made something cool before.
I've also seen The Profession's fight frame-by-frame. I found that very enlightening.
Another thing is to plan the fight, though I usually do mostly improvisation, I like to have a few ideas, as my least well planned fight (I Am The Darkness) didn't turn out as good as it could have. Usually, I think up a few details, and then connect the dots so that all of those things can happen.
Like in Bank, most of the things in the fight I thought up before (like shooting the couch, Majesto flinging the brick, the floor smash, the laser fish, et cetera), then I kinda thought up as I went along to piece the stuff together. One of my favorite bits being the Wizard popping up between the viking and JohnnyBob. I'll usually think up a few shots in advance as I go along, maybe making slight changes during animation.
In addition to the easing, it's very important that the movements for punches to actually get really fast when they hit the guy so it'll actually look like it's going to hurt, and have the guy react in a way which is consistent with said punch, never exceeding the speed of it.
Another thing it to make sure the LEGO people don't look quite so rooted to their simple movements, but try to make it more lifelike, which is hard to do with the obvious limitations of LEGO people, however, it's done quite amazingly in the profession.
As for camera movements, I recommend getting a tripod which can be adjusted, they're fantastic for that sort of thing. And for dolly shots, build something like this: Picture Topic Simply, it's a crank thingy which can be used to turn a twist of the handle into extremely precise tiny increments. I've improved it some since then to be more precise and used it in I Am The Darkness for some ridiculously smooth dolly shots. And I can't stress how epic tilting the camera makes everything.
And another thing is the audio, whether it's the music or sound it needs to be really good, and I thing it does a great deal to make a fight scene that much better, even if the animation isn't absolutely perfect, the sound design, or epic music can go a long way to make it feel a whole lot better. Force unleashed is an example of amazing sound. Seriously, that's some wonderful editing there. And Vango's music just makes it that much more awesome.
Vango without music