Fred "The Hammer" Williamson stars in, wrote and co-produced Boss. It was directed and co-produced by the Jack Arnold.
In Video Watchdog #148, Eric Somer wrote, "Much of the film's mediocrity can be attributed to Jack Arnold's seemingly disinterested direction, which is textbook at best."
Certainly Arnold has shown an ability to handle the genre, with the excellent and underrated No Name on the Bullet (co-written by Gene L. Coon, for those who have an interest in such facts), so the charge of disinterest isn't without merit.
I can't help but see that Arnold may be playing against his strengths shooting this screenplay. It's clearly a post-Leone story and probably would have worked better with the kind of director who looked to find the character through the action, while Arnold is more of the sort who finds action through the characters. Some subtler version of this storyline would have better suited his strengths.
As it goes, it's an entertaining movie with a nice, talented cast and some entertaining moments. I'll agree with others, that aside from the score, there's not much recommend this to the average audience member. I can't say I felt at all like I wasted the time I spent with it, though.
I may be too big a sucker for The Hammer, though.