The show follows three main characters Ethan, a geeky freshman who receives visions, his best friend Benny, a "spellmaster" and his little sister's babysitter Sarah, a fledgling vampire; plus their two full vampire friends, Ethan's dorky friend Rory and Sarah's best friend Erica.
It's not a great show... the acting and writing are both just so-so, but it's on Disney, so what can we expect? It's kind of hard to get excited about any new vampire show or movie nowadays because it all feels like it has been done before. But this one is kind of different in that it's specifically designed for a younger audience, unlike Twilight, which may attract the tween crowd (as well as an older one) but isn't necessarily appropriate for viewers of all ages. (By the way, one thing I did like about My Babysitter is a Vampire is that it pokes fun at the Twilight saga. An important storyline in the original movie is a film-within-the-film called Dusk, which is clearly a parody of Twilight.)
But the show itself is less Twilight and more of a PG-version of Buffy the Vampire Slayer, with a new "bad guy" every episode that the gang must defeat. A lot of the storylines feel recycled, because by 2011 almost every supernatural idea has already been done...
Here's where I'd issue a "Spoiler Alert" but really, do you care?
In the pilot film, Sarah is turned into a fledgling vampire but resists becoming a full vampire by feeding on human blood. This premise goes back to The Lost Boys and was recently also on The Vampire Diaries. Instead she feeds on rats (Louis on Interview with the Vampire, and well, every "vampire with a heart of gold") and then later, drinks a human blood substitute (True Blood). Ethan has visions (like Phoebe on Charmed; Doyle and Cordelia on Angel) while Benny is a spellcaster/witch/warlock/whatever - something he didn't know about and didn't ask for, it was hereditary (the sisters on Charmed; Sarah in The Craft; Bonnie on The Vampire Diaries).
In the first episode, Benny tries to impress a girl by bringing her dead dog back to life, with disastrous results (Pet Sematary). In the second episode, a member of the cheerleading squad is actually an evil witch who is using magic to regain her youth (this exact storyline appeared on season one of Buffy the Vampire Slayer) so the guys dress up like girls to thwart her evil plans (this is a repeated trope in zillions of cheesy shows or movies, I won't even try to list them). In the third episode, vampires are steal blood from the hospital's blood drive (I feel like this happens in every vampire show and film) when it's discovered that Ethan's blood is incredibly rare and valuable to vampires (Sookie on True Blood). In the fourth episode, Ethan's little sister accidentally brings her "Debby Dazzle" doll to life (the kids movie Life-Size) who sucks life energy from others in order to survive (the Succubus on The Gates).
Later episodes include a tree that takes revenge after being cut down (Nickelodeon's The Troop), a werewolf jock (Teen Wolf - both the movie and the TV show; Tyler on The Vampire Diaries; the whole football team on The Gates, etc.) and a love potion that backfires (Sarah in The Craft; Xander on Buffy the Vampire Slayer's second season). In another episode, the guys must protect Sarah, Erica and Rory from being caught by a TV monster hunter (Justin protected his vampire girlfriend from the same fate on Wizards of Waverly Place).
There's really nothing original or special about this show, but I'm sure that kids will still like it because of the whole "supernatural craze" that's just not going away. I will admit that I do enjoy watching it with Lil' Lilith... as silly as it is, because it does remind me of kid-friendly Buffy. Nick at Nite recently added episodes of Buffy to its lineup and while she's old enough to appreciate some of the humor, a lot of the content is still a little too mature for her. So it's kind of nice that she has Buffy-Lite to watch until she's old enough to dive into the real thing.