I wasn't a fan of the finale, but I think the show had a really good run overall. I did enjoy this final season overall.
So much effort was put this season and last into the Barney-Robin relationship, and I felt very sad that it ended just like that. It was so sudden. Once it happened, the ending was pretty inevitable, but I was dissatisfied that it didn't work out in the end.
Robin-Ted wasn't inevitable, and although they spent the first several seasons building up to that finale...that's not what I expected or saw as the most fitting ending (and in feel-good comedies, the most fitting ending is a good thing to me, even if it's nothing special). The show wasn't about Robin-Ted anymore, especially not in the last few seasons, and it was a very sudden pivot to the ending. It feels like they wrote the ending years ago and then decided to stick with it anyways.
The mother was so perfect for him and it worked and while her dying wasn't necessarily a bad thing, it kinda seems like a stop rather than the destination, which was disappointing. It was made pretty clear over and over that Robin was not "The one" (something that was HUGELY important to Ted) so to find out that "oh wait, maybe she is" was pretty disorienting.
Still, the show had a good run. I don't think it fell off as much as people claim (it dragged on a bit but it was never anywhere near unwatchable, and still always had its moments), and I felt a huge connection and investment in all of the characters. I'll be sad to see it go.