I haven't to to MIA since the airport restrictions of 9-11, as well as the completion of construction. I don't travel that often. But from my last experience, it wasn't too bad.
It's a large airport, so it gets a little confusing, especially inside the parking garages when it's hard to figure out what section you're parked in. They try to make it easy on you by naming the garages after animals -- like Flamingo and Dolphin, and further that by reminding you to stamp your parking stub at the elevator -- it stamps your parking section on it. (There's an announcement that plays over a PA in English and Spanish.)
I remember parking sucked -- always full, but that might be different now. And parking was not cheap. Parking isn't cheap anywhere anymore, but I just remember thinking MIA was expensive even back then.
Personally, I don't like MIA; if I can avoid flying in and out of there I do. Luckily, PBIA ( http://www.judysbook.com/members/11971/posts/2006/9/464241/ ) is only 10 minutes from me and it keeps growing bigger so the fares for the places I would frequent are getting cheaper.