Well, I owned a .270 WSM (Tikka T3 Hunterl) for one hunting season two years ago. It wasn't much different than my regular .270 (T/C Encore).
I took three deer with the WSM and two of the three ran a good distance after pretty good hits for some reason. Of course, I have had this happen with my standard .270 now and then too.
Bottom line: The WSM is a good caliber (especially at longer distances than I normally hunt, (tops is around 250 yards here at my hunting lease here in the South).
I do think that the extra pop or recoil of the .270 WSM, cost of ammo for this caliber, availablity in some areas, etc. really isn't worth the extra expense to me and I ended up trading it towards a 1911 pistol. The regular .270 can take just about any game in North America and it too is a super accurate caliber (130 -150 grain bullets).