Notes wasn't a bad idea.
Notes itself was not a bad idea. As it is an application platform based on a document database not a mail system. In fact, the mail and calendar parts simply are applications. Hard-core Notes shops (including IBM itself) has myriads of Notes based applications. So in that sense, it it much more than Exchange for example. It is a very powerful tool indeed.
IMHO what Notes lacks is a good interface. It should have followed current GUI trends much earlier, as quirks in its usability really alienated people. This was sort of OK, when it was supposed to be multiplatform, but it is now basically Windows/Linux/MacOS but does not really have the look and feel, integration, and UX as current apps.
Anon for being a Notes user.