i have been to a couple different ones. there is one in the science museum in san jose, ca where the entire dome ceiling is the screen, with speakers all over the place, even behind the screen. that one is amazing, because you can literally see nothing but screen in there.
there is one in dublin, ca also that i have been to, and that one sucks. just a really big screen, and is crap compared to the one in san jose.
as far as action movies go, i saw batman begins opening night at the dome one, and while it was amazing, so very amazing, i had to go see it again in a normal theater the next day because the action scenes moved too fast. its like trying to sit in the very front row and see everything happening all at once... kinda tough.
personally, i prefer normal theaters unless its something really cool that deserves to be seen in imax