Having Joss as the writer helps. Like many people, I like his funky dialog so his script here is pretty witty. Although, of course, it would've been nice to have the actual actors saying the lines to smooth it over (but, I guess, that wouldn't work in a comic book). The story's pretty good too. As established at the end of season 7, there are now lots of slayers and they've been brought together by the Scooby Gang to help fight monsters. Soon, Buffy, Willow, Xander and the rest are attacked by Amy the witch and a de-skinned Warren who have joined forces and are both out for revenge. Defeating them, they learn that a well-organised and high-tech group known as Twilight are dedicated to wiping out the slayers (see the Wikipedia entry for more details and spoilers).
The story reads like a two-parter of the TV show, although with a lot more action afforded by the unlimited budget of the comic book format. Many familiar characters from the show are brought into this and there are various mentions of other threads (such as the 'fake' Buffy in Rome from the Angel episode "The Girl In Question"). But for some reason, something is lacking. Perhaps it's the fact that the story is only 4 issues long? Perhaps it's a little decompressed with few panels per page? Perhaps it's because it's just not the TV show?
The art, by Jeanty, is generally pretty good. It's clear and uncluttered - I liked it. The likenesses of the characters to their actors aren't bad, although not perfect. Although hardly outstanding, the style works well with the story. The excellent colours by the always-impressive Dave Stewart are bright and fit with Jeanty's clean, smooth lines.
The fifth issue in this TPB, called “The Chain”, feels a little bit like a filler episode. It describes what happened to another 'fake' Buffy, who was sent (literally) underground. The short story, again written by Whedon, is okay, but not as good as the main part of this TPB. The art by Paul Lee also isn't as good as Jeanty's.
The quality of TPB is generally average to good. The pages are nice and shiny but there are very few extras other than a collection of the covers from the five issues at the back. My main complaint is that the four issues of proper story seem a little lacking - if this had been twice as long perhaps I'd have felt more satisfied. Otherwise, this is an excellent continuation of the Buffy universe.
In summary: Fine.