If you look into Golgo 13 film adaptions, you're more likely to encounter the anime 'The Professional: Golgo 13' produced in the 80's. But little would you know that there were unfamiliar live action films beforehand. This film is what I'd call 'the familiar of the unfamiliar'.
This film came part of 'Sonny Chiba Collection Vol. 2'; a three-disc boxset consisting of Chiba's roles outside the popular Street Fighter films (not to be confused with the videogames) which I found one day (probably better than the three films on Vol. 1). What caught my attention was finding him portray Golgo 13. Having read an English translated first volume manga compiled with two stories of Golgo 13 beforehand, I was interested to watch.
If I could compare this film to the structure of the manga, I'd say it's done a good job. You don't see the title-role most of the time until he attempts an objective at the right time just like the manga. It probably makes sense for who he is; he's an assassin with an unknown past, unknown origin, etc. He's a master at sniping, he won't shake hands, and he only meets contact with the hirer once, unless something goes wrong with the objective.
Sonny Chiba, if I had to match the image of the role he plays, was probably the perfect role for Golgo 13. He has the strong eyebrows, the charisma, and the attitude like the character.
The story's great as well. Rather than follow the same familiar structure of 'waiting for the villain to get assassinated' from the manga, the film takes a bit of a different approach. That, I won't spoil for anyone.
The only downer I'd probably give, is the Japanese dubbing on gaijin (foreigners). It's fine with the Chinese actors, but with the Americans, it looks cheesy and unrealistic in a way. Sure, a foreigner could pick up the language with the accent too, but there's probably a hard chance on the rest to handle that reliably. But despite that, it shouldn't be such a big deal to be taken on.
Overall, in my opinion, you'll probably like this film if you've read the manga at least once. I dunno if those unfamiliar with the series will be glued to their seats for the entire picture, but I think the ol' Chiba action in parts would keep them entertained. Well, maybe. Give it a try at least. It's a stylish 70's flick from Japan to enjoy.