SFMM's is decent and definitely superior to SFDK's, but I would still say overall in California it's SFDK < CGA < SFMM < KBF < USH.
I like SFMM's scare zones, when the actors are good it's pretty entertaining. SFMM's landscape provides pretty good opportunuties in some places and there's a good pool of scare talent in the area. From what I've seen the mazes arent quite the quality of CF or Universal though.
I do like that one special thing they still do is turn off all track lightning on most coasters, so you get pitch black rides. Gold Rusher is especially and surprisingly good in the dark during Fright Fest.
Magic Mountain does have some good terrain to work with for Fright Fest. Lots of vegetation to hide monsters and such.
I disliked it because it was a lousy, clunky, uncomfortable ride. Period.
That being said, I don't care for the B&M stand-up coasters, either, and I've ridden some Togo stand-ups in Japan that were pretty good.
They have different desserts (the Monster Cake and Pumpkin Cheesecake are usually pretty good), and there are a number different cocktails available. I'll probably toy some of those later.
They have Halloween-themed goodies in the candy store in England, too.