Actually Not too Bad of a Jumping in Point
I read X-23: Innocence Lost and a little background on Comic Vine and I found this issue to be just fine for jumping into. Even though I hadn't ready part one, I felt I knew what was going on. (Partly due to Marvel's wonderful intro pages)
So Jubilee the vampire, who we last saw in X-Men #11 (or thereabouts) is now wandering around with Wolverine and Gambit. (I really wish Marvel would get the timelines straight on their X-books because they're both playing important roles in Uncanny X-Men and X-Men: Legacy, respectively) I think she's the perfect partner for X-23. They're both outcasts, both have a blood lust (in different ways), and they get to channel their feminine energy into each other. After all, X-23 hasn't really had a good, constructive female relationship yet. (Other than her mom)
I love the art style and the writing is pretty good as well. I have the next issue queued up and I can't wait to read it to see what happens. I'm not yet ready to add X-23 to my pull list, but depending on how I feel about issue #12, it's a strong contender.