Like, say, Terry Prachett, a good bit of the humor in Sheckley is embedded in the way the sentences are constructed and in the careful management of tone.  Reading a bit of it aloud can be a help to appreciation---and I have heard readers and writers suddenly start to read a Sheckley sentence aloud in the middle of the evening at a convention party.  Hey, Sheckley can still make me laugh out loud while I am reading, and that's a rare pleasure.

This is a collection of good, and some great, SF, by a great SF writer.  Whether you are reading the stories for the first time, or going back to old favorites after too long away, I believe you are in for a treat.

And then tell your friends.