It does feel like a filler issue really, although well-done. Trying to find out more about the upcoming battle with Twilight, Willow takes Buffy to visit the demon Sephrilian, who submits them to visions of their past and future. They don't learn much about the upcoming battle except that someone will betray Buffy, and that Sephrilian supports the opposition (enough excuse for Buffy to slay him and mean one less soldier for Twilight's army) and it's strongly hinted that Willow is uncomfortable with the idea of her own side winning, since it means "the death of Magic."
For the most part the story ties up loose ends: We find out how the army of Slayers is being funded (in short: Crime, and an indication that Buffy is abusing her power,) why Willow has been keeping Kennedy away from Buffy, and exactly what happened between Dawn and Kenny-the-Thricewise that made him turn her into a giant.
Possibly another reason this feels like treading water is that it's the result of a competition on the Dark Horse website, for the most inspiring "Buffy changed my life" story, with the winner being drawn into the comic. So Robin Balzer, a schizophrenic who used Joss' TV shows as a point of focus, becomes the guardian of the temporal instability that surrounds Sephrilian. Whedon integrates her well - the character doesn't appear gratuitously, and it wasn't apparent she was a competition winner until the letters page - and interestingly weaves her own unfortunate circumstances into a figure of strength, a character who straddles various realities. I wouldn't mind the fictional Robin reappearing, and Willow implies she might.
Art is by Cliff Richards who apparently drew the original spin-off comic, so the characters look like who they're supposed to be but his style's a bit blocky and cartoonish for my taste. As ever there's some great one-liners and the issue's never boring, but may be one of those that takes on more meaning once the season's over and we can look back on it with hindsight.