What makes a great series finale?

Last week we talked about good movies with bad endings and how we would make them better. This week we discuss television series finales and what makes a good one. 

Does it need to tie up loose ends in a pretty bow? Does it need to infer continuation? Or does it just need to be true to itself. 

Char and Tristan go down the list of finales that were great, ok, as well as godawful.