OK, so the first one was a hit for good reason. Decent story, acting, etc. Appealing to the visceral nature of men.
Given that success, they had to do a second one. They shouldn't have.
While the first Rambo movie had a sane, consistent emotional arc which made for a good story, this second one was just a bunch of action scenes stuck together - and not particularly well done ones at that. I'd suggest they fire the continuity director, except there obviously wasn't one.