I give this movie a B+. Very entertaining, however they dropped the ball in 2 huge ways that keep it out of A territory for me.
First, for the Big Reveal, how you gonna use graphics that look like a cut scene from a 2012 video game? I don't even think it was mo-cap. It appeared to be a completely CGI 20 y.o. Sly Stallone, and it was BAD. The man has been on film for 50 years, you couldn't do a decent de-aging a la Michael Douglas in Ant-Man? If I hadn't already guessed the big reveal, I'd have been more miffed.
Which brings me to point #2. How many times do you need to show a faceless figure standing at an Iron forge? After the second or third time, it becomes painfully obvious that they're intentionally avoiding showing you his face. Which can only mean one thing, the villain is the face we already know. It's movies 101, I don't make the rules.