Have you restarted or reset your iPad?
Restart the iPad by holding down on the sleep button until the red slider appears and then slide to shut off. To power up hold the sleep button until the Apple logo appears and let go of the button.
Reset the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons.
I have no problem with network speeds. The problem is in quality of videos when also HD videos have a noise now. Colours are like washed by a soap - contrast is little bit low than before and even the details in videos are worse. Nothing horrible, but it was better with iOS 5.0. This problem already was there with some version of iOS 4 closely before they replaced it in iOS 5. It was so much more worse, this is only remotly similar. If anyone can compare two iPads with different versions of iOS this will be a proof. :)