I was a sysadmin at a company using Notes/Domino (v 4.5 when I started, up until v 7, when it was replaced by Exchange/Outlook). It was mainly used for e-mail, plus some minor apps for HR.

I used Designer to improve a bit the UI of the e-mail app of Notes. In general I have positive thoughts for both Domino and Notes, as e-mail server & client. Nevertheless the majority of colleagues complained, mostly due to Notes being different from Outlook I think.

Yet, one day, a fellow colleague, a young beautiful woman (marketing, not an IT geek or something), came in IT office to announce us her resignation. Before leaving, she asked if it's possible to give her the Notes installer to install it on her PC at home. She disliked Outlook & Outlook express and really liked Notes :) (v5 at that time if I recall well). We were all stunned and of course gave her the installer and a guide on how to setup her yahoo or hotmail using pop3 or imap.