Article in the works, might become a 2 part feature since me and trinidefender will be talking about quite a few things, and not all solely unique to the williams wing.
I've been going through the numerous pictures of this thread and the FW35 thread (a big thanks to Stefan_!). What. A. Huge. Contrast. Last year they showed up already at China with 3 different front wings.
Main planes, cascades, endplates and upper elements all changed several times throughout the season. In Monaco last year they showed up with the 2012 wing.
Again, a huge contrast to this year. So far I only noticed a small change to the endplate in the entire season. Everything else was fine tuning with gurney tabs and flap angles.