I have hunted with folks who have used it on hogs and it worked fine. I realize deer are not hogs, but size/weight-wise the there is something of a reasonable comparison.
While it is marketed as a varmint bullet, it can certainly handle much larger game such as deer without much problem. HOWEVER, and this is a huge however, these rounds will come apart into a million pieces which means you will definitely be polluting the meat at and around the wound area with bits of copper jacket and lead particles. Wound channels may be quite large.
I would expect that the bullet, or parts thereof, will overpenetrate on smaller deer. On larger deer, the bullet is likely to be contained within the deer and if the deer runs, you aren't apt to have a good blood trail without an exit wound.