This seems like a good idea. It also solidifies the ability for the CAS to offer computer-based exams.
One of my big gripes as an exam taker was that it was clear exam difficulty varied from sitting to sitting (despite the best efforts of the exam creators). Having an item bank will allow a much more robust method of making sure everyone is tested at the same level of difficulty. This seems like the biggest 'win'.
It also felt like item writers sometimes stretch to write strange questions because everything else has been tested and can be memorized. This eliminates that and makes it more likely item writers create reasonable questions that are practically useful to someone in the profession.
On the other side, I found the Examiner's Reports to be incredibly useful. It's too bad those will go away. It would be nice if they can find a way to keep regularly releasing questions that get "retired" or something so students have good reference material as to what will be asked.
How do current exam takers feel about this?