If it's crap ... We'll tell you
I know what you're thinking: "That show is for high school girls. Why would I want to waste my time?" Because, really, this show is better (and darker) than it has any right to be. It is, for the most part, character-driven, and those viewers who get sucked into the show will keep watching because they will genuinely care about the characters.
In Season 2, the writers continue to expand the mythology of the vampires and witches, while adding the requisite werewolves to the mix. While there is nothing shockingly new about the mythology, or the relationships between and amongst the supernatural beings of this world, what makes it really work is the emotional response of those characters to the events they are inevitably drawn into.
Although the show is basically character-driven, there is a plot: one of the original vampires is searching for Elaina, and Stefan and Damon must protect her. It seems very simple, but the writers actually throw us a couple of twists while managing to use that plot as a framework to develop each of our main characters (and even some ancillary ones), not just the three leads. We also learn more about the characters' history - and I'm a sucker for a good back story.
The second season of The Vampire Diaries is darker and more violent than even viewers of the first season would expect. Torture is a regular tool, employed by both the "good" and "bad" characters (inasmuch as the terms apply to characters whose motivations are anything but black and white), and the body count continues to rise. In season one, we lost a couple of characters we thought were major players; in season two, we lose characters we have known and loved. Not just one or two, mind you. The only actors on this show with any kind of job security are Ian Sommerhalder (Damon), Paul Wesley (Stefan), and Nina Dobrev (Elaina/Katherine). Even with the amulets and talismans which have become the standard plot devices employed by the writers, they've had the good sense not to use any of them as a cosmic reset button. The only real bone I have to pick with them is that they don't seem to know the word "enchanted," a verb which is pretty important when you're dealing with magical artifacts week in and week out. (Instead they use "spelled," which I know isn't helping me make my case for this being a worthwhile show, but I just had to bitch about that a little.)
One of the strongest aspects of The Vampire Diaries is its pacing. The show never drags, the plot is never lost, and every episode moves us along toward the tragic climax (and cliffhanger) of the season finale. In a genre that sometimes suffers from "throwaway episodes," this show never falls victim to the need for lightheartedness and comedy. While some shows (Supernatural, I'm looking at you) benefit from the occasional "light" episode, The Vampire Diaries would not, and I appreciate that the writers have the good sense to steer clear of such pitfalls.
Dark and dramatic, emotionally draining and violent, the second season of The Vampire Diaries is a program that's worth spending your time (and money) on.