I just finished my first diplo victory, and while I enjoyed the game, it wasn't directly because of going for it. It takes so long to earn the points that I got to see a world where all the civs got to the high tech units, got to experience the full breadth of climate change, and got to experiment as I knew I was safe, being friends and allied with most everyone. The last 30 turns turned into a real slog, because when I thought I was about to get the win, the AI all voted against me. But if you lose a vote, you get the diplomatic favors refunded, so I just had to wait for the next round of voting. Didn't get there as an aid emergency and the victory point from the civic finished it off, but it was a foregone conclusion.
It certainly feels like a fall-back victory. I went in gunning for it (to complete that hall of fame banner), so I waged 0 wars and just felt like in the end, I wasn't really doing anything to earn the victory, just waiting to hit it. Probably could have won a science victory sooner and certainly could have had a culture.