I've never seen Othello, so I can tell you right off I don't know how accurate an adaptation it is, but All Night Long is a retelling of Othello in the 1960s jazz scene. (The one thing I do know about Othello, "Othello's the fellow whose wife ends up strangled," only kind of happens.)
Jazz musicians Aurelius Rex and Delia Lane are celebrating their one year anniversary. Delia, a singer, quit working when she married Rex, which doesn't sit well with Johnny Cousin, a drummer, who wants her to join a band he's putting together and trying to get some bigwig agent to represent.
So, like any good Magnificent Bastard of filmdom, rather than just go ahead and be straightforward about things ('cause that never works) Johnny goes around the party and tells everybody lies and half-truths in order to turn everyone against everyone else and split up Rex and Delia.
Everybody at the party seems to be friends with Johnny, if occasionally in a "what a jackass that guy is" kind of way. They all seem like they've known him for years. With that in mind, I want to know how the heck do none of them know he's a lying sonofabitch? Why does nobody go "Wait a minute, what ulterior motive does Johnny have in telling me this?" If I knew the guy, I'd always suspect an ulterior motive. (Even his wife mentions he's never told the truth in his life.)
In spite of that, I really liked All Night Long. If I ever find a copy for sale, I'll buy it. It was interesting, it made me want to read Othello (if only so I'd know what was different; I doubt Othello all takes place at one party) and it was, in general, just plain ol' entertaining (my movie priority number one).
If there was anything about it I didn't like, it was that the movie kept pausing to show jazz numbers. That would be fine once or twice, but it happened frequently enough that it kinda messed up the momentum of the movie.
Overall, that's barely a complaint because the music wasn't bad at all (even though I'm not really a jazz fan). It just cut into the plot a bit. If I'm complaining about the presence of good music, I'm not really complaining at all.
And my favorite thing about about the movie was in one of the musical interludes (the one where Johnny Cousin was playing): Either Patrick McGoohan is the greatest faker ever, or that man really knew how to play the drums. Just when I thought he couldn't get any cooler.
End of line.