How much interest has there been? According to BlackBerry's official DevBlog:
There have been over 1,500 app submissions as of last Friday and over 6600 new developers registered in the BlackBerry App World™ storefront. We have teams working around the clock to approve vendor registrations and app submissions. Because of the high demand, approvals are taking longer than normal – we appreciate your patience.
Vendors do have to be registered by the 15th of February though in order to take advantage of this offer. So if you're a developer that was thinking about submitting an app not totally complete in order to make the deadline, you know have a couple of more weeks to get that app polished and ready to go.