I have the appradio 1 in my truck. It is definitely one of the worst head units ever made. It freezes up all the time, take 60 seconds to boot and has all sorts of UI issues (example: you can't see the clock when listening to music!!!). The list of compatible IOS apps is tiny and hasn't grown much in the past year. There is only one halfway decent navigation app. Worst of all pioneer stopped supporting it very early on with no new updates to fix the issues. Once people upgraded their phones to IOS5 they suddenly lost tons of functionality or ieven worse if you bought the new iphone 5 your head unit is now just an AM/FM radio.
All of that said I don't feel to badly about the purchase. I got my head unit for $159 shipped from a black friday sale.
I have heard that the android version is a lot better. Apparently there is a way to get full screen mirroring to work with a jailbroken phone. If that's true it makes the appradio a much better deal as 100% of your apps would work on the HU screen.
I think there is another brand (alpine perhaps?) that makes a head unit that can pair with a few select apps. I know it can do pandora and garmin gps. That is what I am going to upgrade to later this year.