The film tries to recapture the feel of the 1960s, as embodied in the original. There's a lot of 60s-ish set dressing (clothing) but it fails to capture the look at least as I remember it. Setting things in that era gives the filmmakers an easy villain - WWII Nazi holdovers were a real thing back then. But really any faceless villains would do for the level of depth in this film's plot. They're bad, the guys you are rooting for are good, you know what happens next.
And if the film has a singular flaw, it's that. On the one hand it's cartoonish and tries to keep the violence at arm's length. Lots of people die but you rarely see them die or be dead in front of you. There's no gore to speak of, and things are kept relatively light-hearted. But then there are these tortured backgrounds for the three characters about how none of them wanted to be doing this and they're all at the mercy of various intelligence agencies that have kept them out of jail/gulag and that could have been interesting. It certainly forms a part of the Solo/Illya interaction and how they respond to each other. But the next moment the film veers back into silliness with a car suspended in mid air because alley walls narrow, or a truck drives off a dock landing on the bad guy's boat in a manner most reminiscent of Wile E Coyote's anvil descending on him.
It's not that the film is bad at either light-hearted spy romping against cartoon villains, or at serious introduce-the-franchise-characters'-back