Several folks here hit the nail on the head.Duke Michaels and RYBO especially from my point of view.You don't need it to kill deer,even big old cagey deer.Will it help I believe it will,but it isn't even near the first places you should be spending your money on hunting equipment.
Woodmanship,meaning understanding deer behavior and the factors that influence it is first and foremost.As RYBO said if you are spending money spend it on things that will keep you comfortable and dry.
Good luck to you! I hope you have a blast!