Lotus, then IBM have provided us with an excellent platform to build upon. It allows us to directly and fully answer (internal/external) customers needs in a reliable fashion. Despite some rocky times (everyone has their Dark Ages), overall Lotus/IBM have listened to the user base and moved the platform forward.
Business Partners have made a fanstastic impact in helping deliver real solutions to real needs quickly. Notes/Domino almost defined RAD in a practical way, and the BPs took that an ran.
The ND community is a wonderfully diverse group of folks who have put pressure on Lotus/IBM when needed and really helped move things along while still being fun and nice to be around.