I've been checking these forums daily for problems updating to iOS 9.0.1 then 9.0.2. My iPhone 6 plus attempted to download via cellular in Settings -Cellular, I turned off cellular update in Settings which stopped that update cold. I deny all requests to update when on wifi.
I'm happy using iOS 8.4.1 until this is fixed..
I'm not sure if this statement is correct, here it goes. If you backed up your entire iPhone directly to iTunes prior to this update why cant you restore to that last backup? The only issue I see are people whom do not backup the entire phone and think a backup to iCloud is the same.
FWIW, the wheel in Software Update is spinning but not downloading in either wifi or cellular.. Once the new update is offered I'll wait to see how everyone else using iPhone 6 plus, updates are doing and/or if they're reporting problems.. Only after fully vetting the new update, will I allow it to do so on my phone.. I've learned a lesson a few years back and won't make that mistake twice.
Even using 8.4.1, I notice more battery drain then usual. Moreover, I have been using my 6 + more now, then before.. Lazy I think.
In closing and for the record, I'm not an expert but I did stay at a Holiday Inn Express last night.. Sorry I couldn't resist.