I love my duramax. 2002 with the same injectors it left the factory with (160k ago). That's really the only issue that the LB7s had (01-04.5), and if you add a lift pump and a good filter you can go longer than most gas trucks live one one set. The LLY (04.5-05) has a couple very simple overheating problems, but if you spend a few hundred on a new turbo mouthpiece and egr delete they're plenty reliable.
About them being overrated... they're certainly not slow stock, and they've got tons of potential for huge power. At the end of last year a street driven duramax ran something like 9.4 seconds at 149mph in the quarter mile, weighing 6006 lbs. Not too shabby.
Chedisme, if you want to take a ride in my truck, and colins (01 CTD), and wades (97? powerstroke) at nacfest, you can see how they compare and judge for yourself. Ill even put a stock tune on mine for the day