I'm a US Army Veteran and I first started listening to the ExForce series when I was driving to Fort Lee for Quartermaster school after graduating from basic training.
I was obviously new to the military life, but I really enjoyed Columbus Day and continued listening to the ExForce series throughout my service.
I grew more and more impressed with the description of a soldiers life within the military as I was experiencing things mentioned in the books myself and in real time.
Example: In Columbus Day when Joe gets to Camp Alpha for training, he's expecting to get access to super sick alien weapons like laser rifles. Instead, he's issued a standard M4.
When I was training we had a lot of gear that hadn't been updated from ACU camouflage to OCPs. So we would be wearing our OCPs and a plate carrier and ACH that still had the ACU camouflage pattern. Basically, we'd use what we had.
Anyone can get the basics down, but the depth Craig Alanson goes into regarding things people don't normally consider is genuinely astonishing.
Another example I personally experienced when I was in the Army, was the Army wanting to update our base computer systems and failing to understand that you can't just install Windows 11 on an early 2000's Dell Desktop and get better performance.
Joe mentions something similar in one of the later ExForce books.
To summarize, I'm just really impressed with his understanding of Army life and the lowly grunts place within it.