Clozapine is a "we've tried everything else and nothing sticks" sorta med. I've been on it and honestly it's a good med with side effects similar to olanzapine in my experience, but there is a lot of red tape with it (handling the blood work can get pretty complicated in a messy system). It worked well for me, but I couldn't handle the blood work being done wrong, the results getting lost or not sent over the the pharmacy, or my CBC being slightly off and not being able to pick up the prescription until I get my blood work again.
I'm on Haldol now and it's working great but I have to take valium and amantadine for side effects (but if I were on clozapine I'd likely take provigil and metformin for side effects anyways).