Jeremy built the form to work as you'd expect. You can tab between the "blanks" just the way you tab between standard Web form input fields. You can click on any "blank" to start entering text. The password "blank" masks any characters you enter just like a standard password input, and the whole form manages errors if you answer any questions incorrectly. In other words, it works like a standard Web form but it looks quite different. The presentation is inviting and fun, which is quite unlike a standard Web form.
Narrative "Mad Libs" format for signup forms was used in the several A/B tests and *actually* increased conversion by 25-40%.
I find it very cool. What do you think?