FYESKIP  We've used NUD for many years, possibly since before 4.0 (my memory's not so good anymore). We don't use the Contact portion, so I've nothing to add or subtract there.

For the most part it works great, allowing us to keep track of our business obligations, both sales and meetings. We have run into a problem, and perhaps someone has a solution:

Appointments that are on the calendar can too easily be altered or deleted by mistake by someone viewing that data. A mistakenly hit key or space bar can completely change the details of an appointment, and that doesn't begin to address the errant swipe of a mouse that moves an appointment, etc., from one date to another.

There isn't any way to lock appointments permanently, or have a dialogue box come up that questions an edit, intentional or otherwise. Assigning owners and passwords only means that others need to supply a password *once* and they have the right to edit forever.

I'm shocked this hasn't been addressed; why have a database that's meant to be shared and not have a way of protecting the data I've input? Other than this it works great.  
(Version 5.2)