Possibly the worst engine ever made, as said they have four seperate heads and gaskets, they are an absolute bastard to work on, frequently go wrong and cost a bloody fortune to repair.
I run my own business in the motor trade and I won't touch a VM engine now, last one I did was about three years ago, replaced all four heads, the owner almost had an heart attack when I gave her the bill, and that's despite warning her of the likely costs before hand.
Go down the TDi route, you'll not go far wrong there.