I feel the same way... NUD has been my calendar app since way back. As one of the many people that downloaded the public beta, I found it to be one of the worst experiences in my life. Since I do beta testing (and other stuff) for companies like Adobe, and others, I should have seen that as a sign of things to come.
In my opinion (and it's just an opinion), they released the beta too soon, and when the app when out for sale, it still was too buggy for public consumption. It was almost like they stuck it out there to get an infusion of cash in the hopes that it would keep the company afloat... and then the bottom gave out.
I don't use the program like some power app people... To me it's just a really cool calendar. With that said, if I could have my wish, it would be that they somehow pull it together. I guess I'm saying that I'll miss the quirky program... ;-(