It's been a very good engine, IMO. Can't think of many pattern issues with this engine.
GM does make some very good engines. Two that come to mind are the Buick 90 degree V6 and the Chevy LS V8.
The now discontinued Buick 3.8 liter V6 (2009 ?) ...which in one form or the other had been in existence from when the '62 Buick models were introduced in late '61. Even Jeep took over the manufacture of the engine from the late '60's to the mid '70's (?).
Then there's the LS series of V8's...excellent engine and it seems to have taken over from the small block Chevy V8 as the hot rodder's engine of choice.
Then of course there's the small block Chevy V8, the big block Chevy Rat motor, the Buick nailhead V8....I could go on, but my purpose is not to enrage others. ;):B
Suffice to say there have been some excellent engines...also the Ford 300 inline six and Mopar 225 slant six, just to name two. There have been many others.
Think the Duramax fits in with these other excellent GM engines.