I never found S60 to have a steep learning curve at all...though, while I had come from Windows Mobile devices, my first love were PalmOS devices, and that may have made it easier. Symbian and Nokia seem to have taken a lot of cues from Palm in making the S60 interface, when it comes to the simplicity and the standardization of interface elements between applications.
The one piece they cloned from Windows Mobile is the ActiveStandby screen, which is one of the worthwhile pieces of WM IMHO...but S60 fixes it so the user can choose which icons show up in that ribbon thing where Microsoft doesn't.
As far as BB being a stellar mobile communications device versus others....to be honest, they're all getting that way. S60 is a great stable platform for mobile messaging, with support for BB and Exchange, as well as standard POP3/IMAP. Windows Mobile is pretty decent: fewer connection options out of the box but WM6 offers rich-text e-mail now, which is a nice feature at times. BlackBerry, on the other hand, has had to move towards offering more multimedia in the form of MP3 players, cameras, and A2DP support to satisfy demand for these features. From what I've seen they seem to be doing OK with it, but I think they can't really connect with Exchange unless a version of BB Server is present. This is an added expense, whereas Exchange 2003 and 2007 support pushing to WM devices (and S60) out of the box without add-ons.
Each platform has it's ups and downs, but I really don't think stability is an issue anymore...I reboot my WM6 device once every couple of MONTHS. About the same with my old S60 N75, and my family's BB Curves. There's a couple of things I don't like about each OS but I find myself most comfortable with S60, then Windows Mobile. I'm getting familiar with BB in order to test them for the office, and they seem to be a good fit there (especially from a remote/central management perspective) but that's a different priority set that may or may not be worth the added cost of BB Server. And I don't think we'll be able to wait for the Bold...to be honest, I'd prefer to deploy the proven Curve.
Anyway, sorry to get off topic a bit, but it is pretty likely that the E71 and the Bold are going to go nose to nose.
