As a developer, I'll say that App Store reviews are most often not very helpful to me. The developer can't contact the person to get more details about the issue, and issues are often described in not enough detail to do something about them. Contact the developer directly if you want something to get fixed.
App Store reviews are recommendations for other users looking for an app. Because problems you might encounter on a beta OS are very likely to not be the app's fault, it'd be unfair for a review to tell the world that an app is broken when in reality it's likely due to a bug in a beta version of the OS. This happened a lot in the past, staining the reputation of developers who often can't even release a fix until the App Store starts accepting apps built for the new OS at the end of the beta period.