Well ... after many a successful update I can say that RU5 has been the worst experience.
1. Install wouldn't start because Transport Service was hung on stopping. After waiting 1 HR!!!! all but MAD had finally stopped. Given it's 3 AM I finally lost my patience and restarted the server since the update hadn't started applying.
2. Restarted and services started up normally. Reapplied RU5 and this time the update goes through. YAY I think prematurely.
3. Reboot and service failures. Go into Service Manager and all but a couple of my Exchange Services are disabled. Obviously the successful update forgot to reset the service startups to the appropriate pre-install state. I dig around and figure out what needs to be what and start services. Great, I think ...
4. OOPS, forgot about IIS and a few other services the installer disabled. Reset those.
5. Try and logon to OWA and strike 3. Blank page though I've never customized logon.aspx. Still trying to figure this one out.
Seems like this one was pushed out a bit early!