The exam will go from 4 hours to 3hrs 15 mins as there will be less new material to read in the exam room. Lots of information will now be in the presentation material that is published in advance.
Personally I would prefer the new system. It seems to me that going into the exam with some pre-knowledge! about the case study would be much less nerve-wracking than being presented with a very large amount of new information in the exam. (Note that some new information will be presented during the exam.)