Okay THIS is a topic that's worth registering for in order to reply on:
I'm still using my Psion Series 5mx; have been on Series 5/5mx for ELEVEN years so far... you could say I am a devout Psion user. As others have commented, the awesome keyboard wins for me. The applications are made for mobile, like the Agenda's "busy" view that gives you an overview of when you have a free time slot for this new schedule item. Not even the iPhone has that. No modern smartphone/iPhone can survive a week without a power adaptor - my Psion runs for three weeks on 2 AA cells. None can match the typing ease of the Psion. I frequently write pages of text, but forget about that on any modern smartphone/iPhone.
I've tried various Windows Mobile smartphones and they basically suck. The hardware is pitiable and the software is deisgned to run on XP with a big screen, not in your pocket. So I probably won't ever own a Windows smartphone again. (Actually, the software "Pocket Informant" raises any smartphone from horrible to acceptable, but the hardware still sucks.)
I've seriously considered getting an iPhone, especially after having used a colleague's iPhone. It really is an elegant piece of work, and it works intuitively. However, there are still serious drawbacks over my Psion: Slower keyboard, no copy/paste, no file system - and no "Word" application!?! I consider the iPhone a super-brilliant MP3 player, but it's not a mobile office like the Psion always was. In fact, I'd just like to improve my Psion with GSM phone, Bluetooth and WLAN, then I'd be happy.
I am considering what alternatives I have. An Asus Eee 900-series is a good Psion replacement but too large to lug around always, and still has no phone - just like the Psion! The iPhone is pocketable and oh-so-attractive but it would require me to downgrade my writing requirements. I haven't decided what to do yet. But I am realizing that I cannot go on repairing my Psions. Their era has come to an end.