I've heard of many people deleting their FB accounts lately, including people who were using it quite a bit even very recently. G+ is one reason, and the recent changes are another, but probably the biggest reason is FB's really awful policies with regard to privacy and sharing/selling of your personal data.
If you're going to delete your account, I'd suggest deleting the content (notes, photos and videos) several days before you delete the account. I've heard deleted account is purged as long as the account is still open... and they only hold onto your stuff if it's intact in an account you ask to close.
I'll keep my FB account for now, but I won't for a second kid myself that anything I post up there is "private," and I'll always assume they'll sell any of my information they consider marketable.