I'll be the 5th S60 user then, by your count
Oh, and I'm under the age of 70, too.
I use my S60, erm Symbian Platform devices (I currently have a Nokia N73 that's still going strong) heavily for Web browsing, listening to music - and Scrobbling it to my last.fm profile, reading PDFs, taking photos, and as an alarm clock (with an older version of Alarm Manager to resolve the "can't have multiple alarms, or recurring alarms" issue). I also sometimes play games, plus I've dabbled with Python for S60 and the Mobile Web Server tech demo.
Did I mention that they're also really great phones in terms of audio quality (for both calls and multimedia), and have sane antenna designs so that they're capable of actually maintaining network connectivity - even if you hold them in an unusual manner (unlike one of Apple's recent toys).
As someone who's owned a Sony Ericsson dumbphone, I can say that although they have some nice gimmicks (e.g. support for geotagging photos via A-GPS, a Bluetooth remote control feature, and USB Ethernet emulation/bridging), and last for weeks on two charges, their UI makes me want to throw them against a wall occasionally.
As for this Opera Mini beta, it feels significantly faster than the J2ME version, and being able to use the native input mechanism for entering non-alphanumeric characters is a nice bonus.
Disclaimer: I happen to be a Symbian Platform developer and SF community member in my spare time (when I'm not studying at university), although this is entirely my own opinion.