Hum. Well, I updated my iP 5s to 8.0.2, no problems. But the first HealthKit enabled app I use came available via update about an hour ago: Garmin Connect. The update is fine, and I see all my cycling data in their app...but it won't request a connection to the Apple Health app, and populate the data there.
If I had to guess, I'd say there's an issue with the Garmin app. Their stuff is known to suck.
Any devs know how to force an app to request access to "Health?"