I've had a 2004 for 1.5 years. In that time it's had...
1)Carpets were soaked and floor starting to rust. Took it to the dealer who blamed it on a bad aftermarket windshield replacement. I believe them, it's a mess. But at the same time, they did a TSB on the sunroof drain system. I ended up gutting the interior, fixed the windshield, and re-fixed the sunroof drain systems. Cost was almost nothing (some misc. sealant) other than 2 wasted trips to the dealer.
2)The first winter, while using cruise control, the engine would "hiccup" after cruising for too long at one speed. For a while I thought there was a serious problem as it got pretty severe, one trip we were wondering if we were going to get home. Dealer said "No problem found". The problem seemed to go away in the spring, and never came back. I thought it would come back in the winter again maybe, but nope. No clue.
3)Leak at the upper rad bleed hose. Replaced with a new ~3" section of 1/4" hose. Couple bucks.
4)Needed new rear brakes, I bought the Ferodo kit from AB, for all 4 wheels for $800 or whatever it was, did the rears, front are waiting until they are needed.
That's it. Not too bad I'd say.
You can see the influence of Mercedes in the build quality.
I did work for them 2004-2006, I couldn't see any cross-over of technology or quality on the programs I worked on (JK, minivan, Ram, Durango, Caliber). Their focus on showroom build quality (panel fit, interiors, etc.) was absolutely incredible, however.