I dont think its that much harder to be honest. The trade off is there is no weird HR interview (yet.....) until Stage 3.
Its a bit closer to Stage 1 - you can either do it or you cant. I dont think its any harder, it just tests different aspects of your ability. Its shows that they are still trying to whittle out those with the wrong or weak skill set for the job before going through the ardous (and resource intensive) interviews and deciding if they WANT you.
There's no leanrning either, which actually I missed because I know the two motivation documents inside out and upside down. Still, that doesnt hurt because you are going to have to know that stuff sooner or later