A couple of years ago my friends introduced me to How I Met Your Mother and I continued watching until it ended. At first, I was upset it would be over, but they'd reached a point where ending it was better than hoping you could continue talking about a partying forty-something group of friends, especially when they were already slowly going their separate ways.
The show definitely mirrored my college friendships: We were unbelievably close in school, but now that we're out and about on our own we develop different friendships and value different things. All of us are working on re-building that friendship but sometimes it's time to let go.
That said, I found an article that pretty much sums up my opinions on the ending. The series worked to diligently to build a relationship between Ted and Robin which is more than that of most exes. The last season was a cop-out: Ted and his children's mother had a few short years, but the writers killed off the mother (she's such a brief character I don't even remember her name). How they did it was heart-wrenching, but Ted turns around and, as his children point out, finds solace in Robin.
Ted's entire journey is to find the love of his life, but he found her at the beginning of the show and we, the audience are jerked emotionally from girlfriend to girlfriend only to come back to Robin. I enjoyed the show, but it would have been perfectly acceptable to end when Ted meets the mother at Barney and Robin's wedding.