I haven't had an MB in for warranty service in a few years, but their service was second to none. The dealers are paid full retail for the work, and they do whatever it takes to make it right. There are no incentives to cut corners on warranty work.
When the transmission on my C-class calved, MB Canada could have done a minor repair (<$500) but instead noted that my trans was an early build and newer versions were much improved. They authorized a complete replacement including torque converter and all related electronics. The final bill was close to $8K. When the bumper-bumper coverage ran out at 160K (they gave me a free extended warranty, but I won't go into it now) the car was virtually like new. I took it in at 159K and the dealer replaced anything and everything that was even suspect. Amazing. The same was true for our lemon E300. To MB's credit, they spent probably $15K trying to make the car right.
So, while I'm not a current MB owner, and might never be again thanks to some very poor experiences, one area where the brand truly kicks arse is in terms of warranty coverage. Oh, and the roadside and trip interruption coverage is AMAZING. One conk-out of our E300 involved them flying us home while the car was stranded waiting for parts, and then flying us out again to bring the car home. Covered hotel costs too. They just made it happen, no fighting with them at all.