As the majority of viewers, I totally hated it.
I could make an huge text about all the things I didn't liked, but I was so angry yesterday I want avoid going to deep on this matter again. I only want to say two things:
1. to the ones who defend Robin regretted not choosing Ted, that doesn't mean she loved him. I understood at the Halloween scene she was jealous when she realized that destiny and "finding the one" was something that happened for Ted (who spent 9 years of our lives defending this truth) and not for her (who never believed anyway). Through the whole show Robin represented that side of all of us that likes to know or to keep someone always waiting, believing and loving us, even when we know it's never gonna happen or work out. To put she and Ted together again in the end is a big consolation prize for her and maybe to many of us, especially like that without any kind of effort, but kills the very essence of Ted's conception for love, which was to find someone who's ready and open to give as much love and devotion as he could.
2. If you don't agree with this and liked the final episode, I'm happy for you. I actually envy you because life goes on and these 9 years were not in vain for you. But if you think like me, I highly recommend you to watch this alternative version made by a fan and take this, from now on, as the real finale.