Only problem we have is that we can't use Bluetooth to connect, it must be connect via the USB cable to allow Entunes internet access. I believe this is a known issue. Bluetooth A2DP works just fine for playing music though.
I think there are some known problems with iOS 5 and the ATP. I have to restart my phone from time to time to get it to connect with the app on the phone. Sometimes turning Bluetooth on and off on the phone works too. Didn't have an issue with iOS 4 though. Apple probably changed something in the newer iOS. I haven't heard of any similar problems with the Display Audio and iOS 5 though.
There's an app killer onscreen in the entune app there you can use... and Pandora's a problem when you use the high quality audio depending on your phone.
I haven't tried rebooting the phone only Bluetooth. Connection is bad though and disappointed with Entune! I like to charge the iPhone 4S when I get in the car and can't with the USB Cord so I've only been using my Charger and no Entune. Just installed Viper 5904 and can auto start the car now with a/c & heat. That should be standard! Remote has color screen with lots of new things to learn.
I often need to turn Bluetooth Off and On, or check whether it connected. This is a pain to do in the car. Here's the solution. On your iPhone, browse to this web page: http://iphoneza.co.za/IconSettings/ Scroll and tap the Bluetooth hyperlink. This will install a "profile" on your iPhone which puts a Bluetooth Shortcut right on your iPhone's Home Screen. If you later want to remove it, you delete it like any other app, then you remove the Bluetooth "profile" in the Settings app. (General-Settings-Profile). Works great.