RIM's approach worked well when the tech wasn't there yet for a pocket-sized device to run an actual mail client. To get the "full" Blackberry experience, there was a Blackberry Enterprise Server between your device and your actual mail server.
Once we started getting devices that could run straight-up IMAP clients, the biggest appeal of the platform was compromised.
I had moments early in the glass-rectangle era when I thought I missed a physical keyboard, and I definitely had physical keyboard devices that I enjoyed on at least a hardware level through about 2009 or 2010, but the overall functionality of a modern glass-rectangle far and away exceeds what I ever got out of a RIM device.