Well, after surfing around and checking out some opinions and whatnot on last night's big Buffy finale, it seems the consensus is that while it was a bit of a letdown, it was an overall satisfying conclusion to the series.
Myself, I think that all things considered they wound it up nicely, if not neatly. I suppose it was left to Joss Whedon to come in and try to clean up the mess that the season became.
Things I liked:
The D & D game.
Principal Wood's little speech upon entering Sunnydale High at the last fight. In fact, Wood was good throughout, especially in his scenes with Faith.
The dialogue throughout was sharp, which once again indicated Whedon's hand at the helm.
Willow's joy when casting the big empowering spell. She had it coming.
Spike bringing down the house. Payback time for the indignities suffered at the hands of the First.
The destuction of Sunnydale. Can't understand why anybody wanted to live there anyway.
Things I didn't like:
Anya getting the chop. I know that it was inevitable that some of the gang was gonna get it, but I had grown to like her character, especially last season. While I was never really sure exactly how much of a demon she still was, I would think that she would be resurrectable somday...at least she had the funny "think of bunnies" scene before she went down. Kinda would have liked to have seen Xander a bit more upset about it.
That whole amulet which "just happened to be the key to victory" business was so typical of the oh-by-the-way type plotting which typified season 7. Someone more cynical than I might say that the amulet existed solely to work Angel into a couple of episodes.
Seeing Nathan Fillion play such an evil jerk, after liking him a lot as Firefly's Captain Mal Reynolds, was annoying.
In general, that was my problem with the whole season: lots of interesting characters, occasionally gripping plots and dialogue, but jeez Louise I wish someone had sat down and plotted the season from episode 1 till the last and made this whole thing more coherent. Depending on the episode, people vanished and returned with no explanation, acted out of character, and gave long and only occasionally effective speeches. Like Peter David says, why didn't the First simply blow up Buffy's house, like he did the Watchers' HQ? That season 7 was as successful as it was is amazing.
The ending certainly left open the possibility of a sequel, or at least a reunion movie or two at some point, so while it may be goodbye, it's not forever. All in all, the Buffy the Vampire Slayer series was always at least interesting and different, and at its best was absolutely brilliant. I'll miss it, for sure.