Fortunately, I liked it. So did a lot of people, insofar as it won the Newbery Medal in 1979.
Eccentric millionaire Sam Westing has died, and 16 seemingly random people are summoned to the reading of the will. This peculiar document offers each a chance to win Westing's millions by figuring out who was responsible for dispatching Westing. A passel of infuriating clues are distributed and the fun begins. It's sort of Murder by Death meets Murder on the Orient Express meets Charlie and the Chocolate Factory.
Just forget about solving the mystery. You won't get any enjoyment (or success) out of that. Rather, just enjoy the characters doing their various things: making ridiculous extrapolations out of the clues they've been given, snooping out the secrets of the others, and just being their absurd selves. For such a short book with an overabundance of characters, the personalities are well sketched and amusing.