It's a starry-eye vampire romance written by a 9th grade B- student with an MTV budget (and soundtrack).
4.0
I realize I'm not really the target demographic, but, technically, I wasn't for BtVS, either.
In comparison to the other recent vampire tales, The Vampire Diaries is decidedly mediocre: better than Forever Knight and Moonlight, but worse than Buffy, Angel or even True Blood. It's a story written for the MTV audience: slick, sexy, hip, but with fake depth and no real substance or serious plot.
The good:
(1) a rather talented cast: all of the Big Three are good actors (I've see them in other things, so I know they can act), and they do a very good job with the material given them. The supporting cast is harder to analyze, as most are unknown, and it's hard to rate them given the rather limited material given them. As a parallel, look at Charisma Carpenter in the 1st season of Buffy: watching her there, it was hard to tell if she could act, given the 1-dimensional nature of Cordelia. (2) Sets are first rate. I have a little issue with some of the lighting, but the sets themselves are appropriate, and very, very well done. Likewise, the costuming is good; it's appropriate to the story, hip without being overdone.
(3) Pretty good dialogue. The dialogue appropriate, and not smaltzy or sappy. Characters don't say stupid things, and, more importantly, they tend to say the right (or at least appropriate) things in a given circumstance. However, its not terribly original, and there's nothing snappy or memorable about it.
Bad:
(1) Too many characters. There's over a dozen important (or at least semi-important) people we've been introduced to in the first 4 episode, and most aren't anything more than forgettable. It's impossible to care and keep track of folks as they pop in and out without really letting us know anything more than that they are Jock #2, or Caring Aunt #5. People pop in and out seemingly at whim, so it's hard to care about any of them.
(2) Plot twists (or should I say digressions) for nothing more than shock value. Just because you do something unexpected (as a writer) doesn't make it valuable. It has to mean something and advance the storyline. For the most part, the twists have been forgotten as soon as the next episode is half way through.
(3) Seriously overdone music. There's way too much, it's too loud, and it distracts from what's going on onscreen. Using modern hits is great for business, but it has all the subtlety of a sledgehammer, which is inappropriate for something that is supposed to be a romance/thriller.
(4) Unoriginal. Frankly, there's nothing here I haven't seen anywhere else, done better. It's a melodrama, dressed in slick, cool, undead clothes. There's no deeper meaning - what you see is what you get. And it's played All So Serious, like just acting as if every scene were The Most Important One In The History Of The World would make it so. All in all, it has the feeling of a 22-part, 40 minute well-produced MTV video. Honestly, as much as I don't like things like Gossip Girl or Melrose Place, at least they're entertaining (or can be, from a guilty-pleasure standpoint). Vampire Diaries tries too hard, and just isn't interesting enough to warrant that level of drama.
Like my summary said, The Vampire Diaries looks like a play written and acted by talented 9th graders, but staged by MTV producers.