I certainly have. And it led me to a little theory: that Lotus Notes' value was in enabling non-programmers to build a certain class of apps. If this is correct, then its value was pretty big (think of spreadsheets). It also explains why programmers hate Lotus Notes so much; systems built this way get messy very quickly (again, think of spreadsheets). But to dismiss the value to users is missing something big and important.
In other words, this dispute about "is Lotus Notes good software or garbage" is beside the point, because it's based on two different definitions of "good software". Software that helps users get things done that they can't easily otherwise do is certainly good by their definition even if it's the greatest garbagey kludge ever known.
(But I never used Lotus Notes, or even, as far as I know, touched a computer that had it installed... this is just based on stuff I've been told.)
Usually when someone has a bad opinion of Notes/Domino it's because he used an old version of the e-mail application at some previous company, and it did have a sucky user interface. But the current version is on par with anything else out there.
"During this time, the developers at Iris used Lotus Notes to communicate remotely with people at Lotus. Halvorsen said, "Simply using the product every day helped us develop key functionality." For example, the developers needed to synchronize data between the two different locations, so they invented replication. "This wasn't in the original plan, but the problem arose and we solved it," said Halvorsen."
From IBM's "The History of Notes and Domino" http://tinyurl.com/2b8wxk
"Inside Notes provides a single place where you can quickly learn about the architecture of Notes" http://tinyurl.com/ytjkf3 [PDF]
Note: I love how IBM's web site uses the famed Notes Icon as it's little Website icon identifier :)
Simply using the product every day helped us develop key functionality.
The feedback loop of eating your own dog food is one of the greatest benefits a software project can have. Here the programmers weren't only users of the product, they were using it as an essential part of the development work itself. That's like putting steroids into your dog food and then eating it.