I got to handle WM today and yes, the articulation is kinda limited for the legs. No worries, the knee can go pretty much 90 degrees but the hip only about 45 degrees. As you can see, the thigh armour kinda sticks a little to high up and that restricts articulation. HT should have engineered some kind of sliding mechanism for that section.
The hands have pretty much the same range as the mk3, the waist a great improvement. You can turn and you can tilt (though I did not dare to try how far it will go due the report of breakage at TW).
One thing for sure though WM is mighty impressive. The detailing is fantastic, it feels really solid and heavy and the manage to hid all the little switches very very well. I actually have trouble finding them the first time.
I dare say WM will be one those really highly sought after HT figure in the near future, probably even more so than the fabled Original Costume Batman.