As of this morning, Philips has removed the app from the App Store to prevent it from being downloaded, but thousands of Hue customers have already updated their iOS devices and have taken to the Philips Hue Facebook page to register their complaints.
Philips is aware of the issue and has said in a Facebook message posted six hours ago that the company is "taking immediate action to fix it" with an upcoming 1.7.3 app that will be available "shortly."
We are aware of an issue with the latest Philips hue app update when used with iOS 8.0 software. We're very sorry if you're having problems and are taking immediate action to fix it.Users who have installed the faulty 1.7.1 update can continue to control their Hue lights from wall switches, the Hue Tap, and from third-party apps. It's also possible to control lights from the MeetHue.com website. At this time, Philips has not given a new estimate for the launch of a fixed version of the app.
In the meantime, please do not update the Philips Hue app to 1.7.1., nor re-install the Hue app, or reset the Hue bridge.
Update 9:25 PM PT: After several hours of error messages, the 1.7.3 Hue app update appears to be working for most users at this time. [Direct Link]