The Emporer's new handset
Having come from Symbian to a startup to spend almost a year developing one of the first publicly available iTunes App Store apps, I can say from experience that the grass is always greener on the other side.
Apple's developer support on the iPhone has been non-existent, and the constant beta-SDK releases which broke basic framework functionality time after time rapidly wore thin. The release and quality control on the iPhone OS is non-existent, and the issues of getting a product to market have been an order of magnitude worse than Symbian. Yes, we also make a S60-series application, so I know what I'm talking about.
Whilst it's true that one would expect this situation to improve as time goes on, I have to say that right now, though I hate to say it, warts and all, Symbian is a better platform to develop on.