Even if you've been religiously reading the emails that all those baby sites send to you (Your baby at 16 weeks: She's the size of a large rodent!), googling everything about pregnancy and signs of labor (you start eating like crazy...um, that's been going on this whole time) and asking your sisters and best friends what their labor was like ("16 hours of hell." "I felt like I was dying."), you still have more to learn.
Even if you don't learn that much, even if it's just one tidbit from each 2-hour class that really makes you think or makes you feel better about what you're about to inevitably do, it's worth it. It's worth it, if not for any other reason, to simply spend the dedicated time at class thinking about your baby and your birth. Putting the mental energy toward your baby. You're away from distractions (ahem, the Internet), you're with a group of people who also want to learn about the labor and delivery process, and you're guided (hopefully) by someone who has assisted with countless births, a few of them maybe her own.
Even if the class, like any learning experience, leaves you with more questions, that's a good thing. It just means that at your next OB visit, you won't meet your doctor with that blank stare, looking back and forth at your husband and her, when she asks if you have any questions. Because now, you will. You'll have questions you didn't know you needed to ask, and she'll have the answers.
And in the end, you'll feel better about and more prepared for bringing your sweet baby into the world. Go ahead, sign up. You won't regret it.
Just take lots of snacks.