...
Visibility on this site is very much like learnability. There is little information scent to direct users to the less frequently used features of the site making their visibility poor. This is a trade off for good visibility of the states the user would normally find himself in where the information is very good linking him from one view to another. Also, the user receives instant feedback on every action they commit, also helping visibility.
Efficiency
An advantage of this design is the efficiency of having most states that the user would want to see available from the original user view. The direct manipulation of bill creation helps error prevention by only allowing "approved" information to be entered into the bill form; however, users trying to create bills quickly will find the direct manipulation will slow down progress by making users need to click more objects instead of being able to navigate through the form by tabs.
...