The role of a reviewer IMO is to call whatever is being reviewed as s/he sees it, and go into some detail as to why s/he sees it that way. So what's a wannabe fanfic critic to do when a fic leaves him incoherent and drooling like an undersexed Dark Angel fanboy in the presence of a tightly-clad Jessica Alba?
Call it like I see it, I guess... just don't expect anything resembling objectivity. Not that any piece of criticism, news or whatever written by the human hand is ever gonna be truly objective --- it's a matter of how objective you try or pretend to be. I'm not gonna bother with either.
This fanfic is one of those that tries to be all things to all people. And succeeds. The premise is simple, if of a large scope: charting the relationship of Willow and Tara over three seasons. The twist is that Tara is a vampire of the traditional "evil serial-killing bloodsucker" school (as opposed to that besouled wimp Angel). This kind of twist has been tried before; generally the author abandons either believability, canon mythology or both, and quality usually goes out the window too. (Let's not even start on the pre-chip Spike 'shippers). Basically, pulling off such a twist well is a hell of a feat, requiring a hell of a lot of careful setup to make it credible. Particularly if the other half of the relationship is noted for her moral conscience (remember "Pangs"?). Fortunately, Zahir put a fair bit of thought into this before jumping in. He opens with a nice "Choices" what-if? situation (always a fan-author favourite, usually with the B/F 'shippers, but nobody else that I can think of has done it this well) and then skips through his A.U. versions of certain key episodes (part of that 9 is for making "Where The Wild Things Are", one of the great Buffy stinker eps, an enjoyable read) until he's established enough plot points of his own to more or less abandon canon.
Meanwhile, for the less romantically inclined (yes, we do exist... no, really...) he knows the meaning of the words "kick arse" (in the literal sense), "blindsiding plot twist" and, most importantly, "shit hitting the fan". Like a lot of good fanfic, if you step back from this and consider it carefully and rationally, there are holes, simple plot holes and stuff that just isn't quite up to the same scratch as the rest of the fic (I won't give too many examples, this is a fic you do not want to read spoiled, but a fair way in the Scoobs go slightly insane, because there's a demon in their presence that... makes people go slightly insane. No inventive or loaded description, not resolved as well as it needed to be, not exactly Joss-worthy. Then again, the same could be said about some episodes...). And like a lot of good fanfic, if you step back and consider it carefully and rationally, you're missing the point. Never mind, it's not like you really ever want to stop reading, and sooner or later you see all those threads he's been dropping tie together and you know within a couple of chapt--- mother of fuck which hell did he pull that one from?
Just like the show at its best, you can see the threads in the previous parts and kick yourself for not picking it, see something of the threads he's laying this time and try to guess where he's going now.
And then the shit hits the fan again...