I have had both WinMobile phones and an iPhone. I could not disagree with you more. The iPhone is everything not only a PDA should be, but everything that every device and/or appliance should be. It is the antithesis of everything that has gone wrong with the consumer electronics industry in the last decade or so.
My advice to everybody here: If viewing Sling streams on your cell phone is that important to you, and you have an iPhone, simply upgrade your SlingBox. Giving up your iPhone would be like cutting off your very functional, well-made, and easy-to-use nose to spite your face.
It really boils down to what you use your device for. I am of the opinion that the iphone is not a good business tool. Business usage is my number one reason for having a PDA in the first place. I primarily use my Windows mobile PDA for email, server administrative functionality, and of course business related phone calls. I do have Internet on the phone so the closest thing I get to using it as an "entertainment" device is watching Slingbox streams of my security cameras and TV over the 3G network. I do not use my cellphone to play music, take pictures, or take video. I have an MP3 player, 10MP camera, and video camera for each of these functions, although the Windows Mobile device can do those functions. I also carry a seperate cell phone for personal use and do nothing but make and receive phonecalls on it, even though it has a camera and all that other crap.
Some people like having one device to do all these entertainment and business functions. Not me. You may have a TV/VCR/DVD combo in your house. Not I. You may have an imac. Not I. I prefer seperate devices. Just a personal preference. When the VCR went the way of the dinosaur I got rid of the VCR, not the TV/VCR/DVD combo. Or, what if one part of a multifunction shats the bed after warranty is up? You live with a partially broken product or replace the whole thing?
As far as my personal cell phone (not the PDA), if I had a choice I would have a phone with no camera, music capabilities, video capabilities, or Internet. It would make and receive phone calls and have a really long battery. There isn't such a thing anymore. Just ask your cell provider for such a device and you'll be told there isn't one.
I can understand why a person might want to simplifiy things and have one device do all things, but I don't want that. I am not wired that way as a person. You'll also find that a device that has all those functions never has been as good as or will never be as good as seperate devices. What are they up to now on the consumer level, 15 megapixels for a digital camera? What about storage capacity for music? Event the stand alone ipods have larger storage capacity than iphones, not to mention other brands. And the built in video camera in a phone doesn't even come close to a stand alone HD video camera. Note that even a video camera that can take pictures is not as good a a stand alone digital camera for picture taking.
Anyway, regarding the iphone apps. There is also a lot of complaining in the industry about Apples tight control over the apps and the app approval process. At least the Google phone (which isn't there yet as a product but I would say has more potential in the long run than iphone for such an everything device) is open source and the Windows mobile phones have tons of third party applications.
Aside from myself as a consumer and user of PDA phones, I know a lot of people that are either business owners or professional business employees and the iphone is not exactly their preferred device for connectivity with such things as a corportate Exchange server.
But again, it depends on personal choice and your needs. If the Apple iphone makes you happy, fine. The only other thing I can say is that I have been using my slingboxes, both a first gen and a second generation highest model for a few years on my Windows Mobile PDA phones. This is all old to me. I'm sure part of the reason the Slingbox app for the iphone won't work on the older slingboxes has something to do with Apples tight control over the apps. If that is acceptable to you, fine.