Reliability of a Mercedes 250 BlueTEC

Does anyone have any experience with the Mercedes 2.1 litter diesel? Are these engines any good? I don't know anything about them or frankly Mercedes either. Never considered one until recently. 

I have no experience with that particular engine.  Pull up a chair and I can tell you all about the horror show that is the OM642 Bluetec motor.  After experiencing that excrement exhibition my advice would be to run, don't walk, away from anything Mercedes especially the diesels.

But then, my opinion might be biased...

Kinda figured that would be the answer which is a bummer since they are such nice cars. 

I've worked on just about every make of vehicle on the planet, including Audi, Mercedes, BMW, and Rolls Royce (think fuses that consist of a certain gauge of silver wire wrapped between two terminal posts). That said, I would not consider any German make as a semi daily driver. High priced parts and often hardwired electronics (= high labor costs) just don't add up for many drivers like me. German vehicles are sometimes more about status rather than a mode of transportation for many of us. They have a place, but not in my budget limited garage. An exception would be a Porsche as a weekend driver and/or racer.

I've had good luck so far with two modern Merdedes as daily drivers over 6 years and about 75k miles, but they were both gas cars and well maintained from new.  07 cls63 and 17 E400 wagon.  The only real repair in my 5 years and 60k on the CLS was a coil pack, subsequent owner did two air springs and upper ball joints.  E400 is new enough to need nothing.  
 

Maintenance parts for the CLS were very reasonably priced except for the AMG specific bits and the car has been very logical and reasonable to work on.  

I wouldn't bother with any Mercedes diesel that comes after the om606.