TV shows are somewhat notorious for having weak finales. In some cases rushed due to cancellation, others symptomatic long past it's prime. Games Of Thrones, Lost and a bunch of other shows pop up. Some like the Sopranos divisive.
Two come to mind that had great finales, TNG's "All Good Things", which is the best finale I've ever seen pretty much and Boardwalk Empire's "Eldorado", where a long running past/present plotline comes full circle rewarding viewers for sticking with it.
Any others come to mind?