I run a number of wifi hotspots, all of which use a captive portal "Splash Page" that is branded per location.
Since the iOS6 update I have been swamped with guests and customers complaining about this www.apple.com "success" page popping up instead of the intended customers login and terms acceptance page. When cancelling it drops the wifi router connection and there is no way to connect to the intended free wifi hotspot.
The problem is in Apple's update, there currently is no way to disable this unwanted feature.
The solution is to go to your Settings>General>Cellular>Cellular Data and turn it OFF when you are at the hotspot location.
Now when you choose the hotspot's SSID and join it......you will get the sign in page from the captive portal and not the "success" page.
Be sure and turn the Cellular Data back on.....when you leave the hotspot.
Apple needs to fix this WISPr function, I am only a small provider and I am sure that worldwide there are going to be hundreds of thousands of iphone, ipad and laptop users who will no longer be able to sign on at wifi hotspots, work, universities, hospitals and hotels.
As a side note: I have an older 4S phone with iOS6 and I cannot join.....my wife has a newer 4S phone with iOS6 installed and even though both our phones are set exactly the same......she can connect without turning off her cellular data and I cannot. Curious?