I think the long and the short of it is it depends what you want/need your device to do and what you are prepared to live without to gain the benefits each platform offers.
Business and security wise the iphone cannot match wm and for user friendlyness vice versa.
I'm a greedy bugger and want both and am lucky enough to be able to do this.
Recently i have chosen to use the combination of iphone and netbook and for me that works fine. I don't work in IT or security or use exchange so for me they are non issues. Are the exchange/security issues really as bad as some say as it's not something i know about? (from your ire i guess they are)
The main reason for this is i like the iphone for media purposes and checking my email accounts. I can then fire off a quick reply where needed or use the netbook for something more involved like attachment editing.
If i was forced to have just one device it would be wm.
Why? it works and works well and has mobile office capabilities, compared to my beloved mda vario which taught me very much and wasted many hours, wm has come on quite a lot in terms of not needing to hack things and install cabs to hit the sweet spot. Now you can pick up the latest device and pretty much use it stock.
It is established and supported very well, albeit mostly through forums. It has the capability to do everything the iphone does and more (although there is a lot of functionality to be gained from hacking the iphone it's not the same).
Still MS needs to produce with wm7 in terms of a useful ui and good media player and of course making it more developer friendly so that it is not left behind.
So wavey you're not alone, in fact i would say far from it. I just get frustrated that every time we get a point release from MS it is on the whole underwhelming and pretty much the bare minimum in terms of what they could accomplish.
Two of my mates asked me which phones they should get last week and are now both extremely happy owners of Touch HD's. Both have never used wm before but based on their descriptions of needs this is the device that suited both best.
I may like my iphone but i still love wm
Edit: once you jailbreak your iphone and install mobilesubstrate and mobileinsatllation and a few other core utilities you can run pretty much anything on it as long as you know how to write the software for it. you can run apps at the same time after jailbreak and installing (forgotten it's name now) a program that allows it and the majority of programs reload in the state they were shut in such as the tabs in safari reloading and the ipod running in the background is not affected by other apps either unless they use sound themselves. I think there is a lot on the iphone you can do that maybe people do not know of but without the inclination or time you are limited to a stock install which has some serious elements lacking.