I run hot and cold with Kurt Vonnegut, sometimes thinking he's a genius and other times silly and simplistic. My response to this tale of the effect of God's utter indifference on the creatures of our solar system is one of moderate disinterest, though I do generally enjoy clever irreligiousness.
"The two chief teachings of this religion are these," said Rumfoord: "Puny man can do nothing at all to help or please God Almighty, and Luck is not the hand of God." p.183
Another part that speaks to me is the Tralfamadorians' process of killing off its native people in favor of machines, especially in the context of the book's 1959 publication date. In identifying more and more of life's activities ("purposes") not worth their time and creating machines to take on these mundanities, they eventually determine that there is nothing not better done by a machine, including annihilating their race. I'm not saying that factory work, for example, is exciting, but I do think we need to be careful how much we outsource to machines.
And here's another element that is either foretelling or still relevant,
Rumfoord had known that Constant would try to debase the picture by using it in commerce. Constant's father had done a similar thing when he found he could not buy Leonardo's "Mona Lisa" at any price. The old man had punished Mona Lisa by having her used in an advertising campaign for suppositories. It was the free-enterprise way of handling beauty that threatened to get the upper hand. p.53
But there is some stuff that is very 1950s. I think Vonnegut's treatment of women and people of color evolved a bit as the years passed, though the former more than the latter to my memory.
There's some clever stuff in Sirens, of course, but overall, I'm sorry; I found it a bit of a bore.