I upgraded to an E51 from an E65. It's great, data connection v.quick with HSDPA for web browsing, Mail For Exchange great, v. reliable email and the phone looks great too.
Only problem i've found is that holding down the # key to switch to silent doesn't seem to work but a Google search revealed that to be a common problem. I just changed the shortcut of holding down the envelope button to bring up the Profiles menu and that makes it easy. The power button on the top seems a bit flimsy (like it could screw up easily like the old 7650 one did).