This is something very new indeed. I had no idea it even existed so I reached out to guys in London and it seems to be in the model of a PST/GMAT.
As expected, they are looking at your quant skills (math, analytics) but also testing your verbal ability (reasoning, logic, reading pace). To practice, I would suggest to maybe do a GMAT test online (you have many for free just google it) and a few PSTs and you're good to go.
My guess is that as it is something new, they are still testing/calibrating it so I don't believe they will put a significant weight on it for now, but I may be wrong.
Any Bainies in London around to share more information on this?