I really enjoyed the ending. I think it a great way to end the series. Overall, I still preferred the first 3 series of the British original to the U.S. version but from a fan point of view, the U.S ending was much more satisfying.
While I may have preferred the British original, the U.S version really grew on me and I really enjoyed watching the 4 friends try and fail so many times in their attempts to be human. Ultimately, being human is about the sacrifices you make for those you love, which they never realized until the end.
I liked that Aidan and Sally got their door together and Nora and Josh had their happy ending. And while I would have liked to see a little more of Sally in the final episode, it made sense that she sacrificed herself for Aidan.