I saw Fast Five today, and it was excellent. "I would pay to see it again in theaters" kind of good (only movie I've seen twice in theaters in most of ever: the new Star Trek movie.) This was a heist movie, more than a car movie. (Think the bastard love child of Ocean's 11 and The Italian Job). It was a movie about family and the choices you make when all of your choices are bad choices (funny, I took an entire class in southeast Asian lit based around that theme). There was actual plot. There was good music. There was a lot of humor (Tego Caldreon and Don Omar are hysterical).
Go see if it you've seen the others, and/or you haven't automatically decided that the whole franchise is dumb (and if you do think that, please do not harsh my fangirling). You could watch this movie if you haven't see the others, but it would probably be more entertaining if you had.
Finally, if you do go see it, there's an Easter egg after the first set of credits that you want to stick around for. It's a bit of a bombshell.