how "good" is our engine?

[f5fstop]

I don't believe this engine was ever used in a Blazer. Normally, a new engine does not go into a body platform that is scheduled to be phased out of production; as the Blazer. The Blazer used a 4.3L V6, and in its early years, had some problems, but in later years, become pretty good.
In the past six years, GM has sunk millions (lots of millions) into engine design and manufacturing.
First of the inlines was the Eccotec 4-cylinder, first released in the L-series Saturn in 2000. Had some startup problems but the engines were returned for the first year for reliability tear down if replaced. On average, for a new engine, very few were replaced, but yes, some were.
The engine become more reliable over the years, and considering the number of these Eccotec engines out there, they are extremely reliable.
GM took this same technology and basic design to the inline 6 and 5-cylinder engines and developed some very reliable engines.
The 6 and 5-cylinders inlines were also beefed for trucks, their primary target. (They say truckers are harder on engines...not sure if I agree, since many of the 4-cylinders had NOx installed within days, and the 2.0L Eccotec runs either a Turbo or Supercharger, and so will the 2.4L.)
From what I have heard, this is a very reliable and durable engine. Will some break? Sure, they are man made. Is there a possibility of a problem during manufacturing for a day or two and some engines sneak out before the problems are found? Sure, this happens in any manufacturing facility.
However, I have one now, and it is the smoothest engine I have ever had since I had the infamous 3.8L engines.
The biggest problem any manufacturer has with any engine is usually due to the electronics (sensors/outputs) and calibrations.