Rockymtn eagle,
The answer to your question depends on the type of hunting you do. For many types of game (deer, antelope, elk, etc) a good quality pair of 10X or even 8X binoculars will stand you in good stead in most situations. However, if you are sheep hunting and have to judge trophy quality or age a sheep at a distance of a half mile or perhaps much more, a spotting scope is absolutely necessary (unless you're fond of long futile hikes and mountain climbing). In the case of some game, like mountain goat, the difference between a so - so trophy and a great trophy in only an inch or two in horn length; impossible to judge without a good spotting scope.
On the other side of the coin however, if you are hunting these or similar species, you will often have a guide who is well equipped with a spotting scope. In any event a spotting scope if a nice item to have at the rifle range when trying to spot holes in the black at 200 - 300 yards.