Noticed strange issues with IOS 6 and VPN, the VPN now just gets the circle "connecting" and does not let me cancel VPN connection or do anything else to stop the connection. Also noticed a huge jump in data usage, because i use a verizon mifi for wifi. The two IP's its connecting to all the time now are Apple and Akamai, this did not happen with ios 5.
I have an open bug report ticket with Apple on this VPN thing. It's been open since iOS 6 was in beta though and I'm not sure they're really looking at it. Anyway, I have been able to get around this VPN stuck issue by doing one of two things. First, you can try to enable airplane mode and then disable airplane mode and try to connect to your VPN again. Second thing to try is to close settings and go back to the home screen, double click the home button and push and hold and then kill the settings task and then reboot the iPad. One of the problems that I think is related, however, is that oftentimes after killing runnings apps and then rebooting, if you double click the home button after the reboot, you'll see that the tasks are there again, like they were never closed. Hope this helps.
Oddly, this problem doesn't seem to happen at all with iOS 6 on the iPhone (4, 4S, or 5).