But that doesn't make it a horrible or bad ending. And the show had lots of sad moments, perhaps it was a sudden change considering the last season, but it had a very strong realism throughout it as a whole.
And I totally agree with you in that last part. The 9th season had few events for most of it, and suddenly everything appeared in the last three episodes, so they should have done a better job by showing Ted spending more time with the mom, and overall spacing out of the things that were all in the last episode. It was really annoying how they seemed to be delaying the ending by making mediocre episodes.
You put everything really well. Barney had this change lots of times in the series, as he had more serious relationships, and ruined them.
And that was the biggest issue, since they saved all events to the very end, it was really dissapointing seeing Ted rushing to Robin again, because it really seemed he quickly got over the mother. That's what causes all sorts of feeling in the ending for me, because when you hear his kids saying "it's been six year dad", you realise he deserves to be happy, and no one should keep locking themselves up, and being alone because they were in love.
But Robin? Saying that Ted was "probably the guy I should've had ended up with" was heartbreaking. Didn't she had feelings for Barney? And worst of all, how will he feel when he finds out Ted and Robin are dating? So the series made big contradictions here.