What makes a good plot "good"? (books and stories)?

Hmmm

A twist, or an unexpected event?

Like

Billy was going to school, jsut hte same as everyother day

Then all of a sudden, an evil sheep appeared and started eating everyone

The thing was, he had to find a way to destroy the sheep without killing it

Because the sheep was actually his mother!

DUN DUN DUN!

See? :]

Unexpected twists and turns, as well as what you already mentioned. I want to read something original, or if it's based off of something else, I want it to be unique, something that I'll remember, since I have a hard time remembering anything about movie or book plots and characters after a few months. If I remember something I liked, or was interesting about a book I read, I'm likely to read it again.

Think of it this way. When you finish a book and you think: "That was crap," well, WHY was it crap? Maybe bad grammar and vocabulary,no twists, no suspense, no action, repetition of thoughts,ideas and happenings,you can't relate to it, it was unoriginal, it was dull. So a good story is the exact opposite! Good grammar and vocabulary, twists, suspense,action, no repetition, everyone can relate to it it was original and the opposite of dull in every way. That, however, is only what I think.

Some surprise twists that weren't expected at ALL.