My friend did it, and she's still friends with her nct buddies (and her son is now 8 years old. I did it, and the only person I kept in touch with i also went to three other (free) classes with, so feel our paths would cross anyway!
Kind of depends on the mix of personalities if you're looking for a group of parent pals. I found the info at nct useful, and helped me think through my birth plan options.