Yes, JustaFied, Decline is a prequel of sorts to Barbarian. Yes, it's worth checking out but it's not as memorable as Barbarian (although it won 9 Canadian Academy awards and a FIPRESCI award at Cannes).
Barbarian is more expansive both visually and thematically. As you've pointed out, the dichotomy between the boomers and the next generation is particularly interesting, and you won't find that in Decline. My recollection is that the prequel is just as funny and perhaps just as sad. It takes place on a single day and it's even more dialogue-driven than Barbarian. The basic thesis is that the boomers obsession with hedonistic pursuits at the expense of everything else is indicative of a society in decline. There are three set ups: the men at Remy's lakeside house, the women at the health club, and a gender clash over dinner. The main topic is sex and the game of choice is intellectual oneupmanship.
Please share your opinions if you decide to watch it.
