There's an almost dream-like tone to much of the film, especially those scenes involving the wonderfully ethereal Shirley Henderson (as Joy), and it can be hard work.
But it's worth it for the way Solondz brilliantly exposes family relations at their most brutal, with a series of compelling but understated confrontations which are deeply funny and unsettling at the same time.
Life During Wartime picks up the action from Solondz's 1998 masterpiece about 10 years down the line, with the same central characters but an entirely new cast of actors playing them.
Bill, sent to jail for abusing one of his son's friends at the end of the first film, has just been released from prison and is determined to track down his now adult son.
His youngest son, meanwhile, is struggling to come to terms with the realisation his father is not dead, as his mother had told him, and to understand exactly what a paedophile is.
The funniest moments generally involve Bill's ex-wife Trish (Allison Janney) and her new love-interest Harvey (Michael Lerner), in particular when he and his oddball son Mark (Rich Pecci) are introduced to her children for the first time.
But it's the zen-like Mark who steals the show, replying to Trish's question about whether he's dating with the classic line: "No. I'm more focused on China. Everything else is history. It's just a matter of time'.
Happiness and the various ways we attempt to find it, usually without success, was the theme of the first film - leading to the brilliant pay-off in which Trish's eldest son finds his own form of happiness and rushes out to the dinner table with the evidence.
If there's a theme to this, it's that of forgiveness, in particular for Bill and for Joy's husband Allen, a (falteringly) rehabilitating criminal.
While it doesn't quite hang together in the way Happiness did, it's worth sticking with for the flashes of brilliance quite unlike anything else you'll see on screen this summer.