I remember catching a lift in the first generation ML. I'd looked foward to it since it was launched as I really liked them. I was SO underwhelmed by it. It turned me right off them. I remained sceptical after the facelift, but after a couple of years I tried again. LOVED it. Completely different car. My ML feels tighter and more solid than my old C-Class. Definately avoid the earliest cars.
I know those prices look very tempting, but it's for a reason. You wouldn't get the feel good factor from those.
If you are a fan of an "agricultural" ride and an interior made from recycled fizzy frinks bottles, and you like panel gaps big enough for an inquisitive cat to climb through, then its THE car for you!