Apparently it was removed Monday morning before the park opened. I'm sure someone from CF will confirm sooner or later.
Angry Birds is a good "bridge" IP between older thrill seakers and children. A wise choice.
My only problem is Thorpe is too small to have themed areas; it seems to me that only the rides are themed. As it stands at the moment, the Det area is a subtle blend between the Amity and Calypso areas. Most of them blend into one so sticking a plasticy Angry Birds theme in the middle of the park at "junction area" might make it feel disjointed.
At the end of the day, no matter how much lipstick Det is wearing, it will still ride like Det (albeit with cheesey soundbites) and two new attractions (dodgems and 4D Cinema) are something to look forward to.
I think they missed a trick not fully incorporating the teacups in the theme. At the moment they're out on a limb. The Tetley sponsorship is probably what's holding them back but it would have been another ideal family ride to include in the rebrand.