I don't usually get my wife to watch many rifftrax / MST3K... But she will occasionally kick back and watch one with me when a subject movie rolls around that she is familiar with. We both liked the first Twilight movie when we saw it on DVD a few years back, it wasn't good but not particularly awful either. It's somewhat passable in the general sense...assuming you can get past the very earnest "we're taking this sillyness very seriously" vibe of the whole thing and just enjoy the pulp romance / popcorn flick aspects.
Anyways, we finally got around to watching the rifftrax... and the guys brought a lot of big belly laughs... the kind where you have to pause the DVD because you are missing subsequent jokes. Always a good sign. My wife wasn't laughing quite as hard or as often as I was.. but she got a lot of chuckles as well. She did say that she probably couldn't handle watching a rifftrax without having already seen the movie because "they talk too much over the actors"... but she is looking forward to watching the next two Twilight riffs in the next week or two.
They threw a lot of riffs out in this one, really rapid fire throughout, and a noticeable amount of riffs fell flat for me... But even so, the high quantity of big home run laugh out loud zingers puts this one amongst their very best work. I gave it a nine.