One of the most bulletproof cars ever. A few things to really be mindful of though. One is the timing chains. On the MB V-8's, they are long and change direction often. They don't last the way chains do on inline engines, so if there is rattling on start up, or idling, be wary. Can run $1000 or so to roll new chains in and replace the tensioners. See of there are plastic chain guides, as that could be a problem.
There were some very minor issues with some of the top end bits, but pretty much all cars have been sorted in that area by now.
The four speed AT is nearly indestructible if the fluid and filter are changed every 50K-km's.
The ACC control unit is junk, as is the cruise control. Expect the cruise to be broken, but if the ACC is, the heat and AC might not work. There are rebuilders that can do a swap for a fraction of the cost of a new one.
Rear door power windows might not be working. If you can live with that, leave it. If not, well, it can be a fairly expensive repair.
Make sure the steering box is not leaking. Can be an expensive repair. Not a common failure, but just make sure.
An SRS light is usually worn contacts between the steering wheel and engagement ring. Easy, cheap DIY.
Make sure the AC blows cold. If the evaporator is leaking, well, that is one MASSIVE amount of labour to repair. Not good. Basically, the entire dash has to come out and then some. Awful.
The V-8 is powerful, and Mercedes realized that the car was barely slower than the vaunted E500, so they saddled it with a horrifically tall final drive. It means you can get decent highway mileage, but the car doesn't seem to have all those ponies. Many savvy owners swap out a shorter ratio (from an E500 or other V-8 MB) and the car is a rocket.
