The interface is AWFUL. They updated their site a few months back, after I had set everything up. If every piece of wedding information I have was not already in this site, I would have switched then, but I didn't. And I am still wishing I had. Their links do not take you where they state they will, they most often lead you to a generic page. You also do not have the option to change your email once you make your account (this is the ONLY webpage that I have EVER seen that on). Most of the time to get to any of my information, I have to click through three or four different links. Save yourself the trouble, download an app to your cell phone. NOT The Knot.
The worst part? When I send an email for any question that I have, it takes over a month to hear back, and by then the question is moot. Don't bother, go elsewhere for your wedding services. After months of planning, I am MOST excited to be done with this webpage.