Storing food in the freezer will generally prolong its shelf life, so at first glance, it seems like a good idea to store coffee beans there to keep them fresh. But the freezer affects different foods in different ways and really isn’t the optimal storage unit for all foods, coffee included.
Consider a loaf of bread. When fresh, it should be relatively moist/soft and tender, but when you freeze it (or put it in the fridge, for that matter), the bread dries out and becomes a bit hard. It stays “fresh,” because it doesn’t mold, but frozen bread is really best for toasting and can’t compare to a truly fresh loaf for sandwiches, etc. This same drying principle applies to coffee, because the natural oils that are released during the coffee roasting process are dried up in the freezer, resulting in a relatively tasteless brew. Unground beans will fare better than beans that have already been ground, as they will hold on to the oils better.
The best way to store fresh coffee beans is to keep them in an airtight container, where the beans will not be continually exposed to air and will be less prone to drying out. You can keep the container in the freezer (still airtight) if you live somewhere very hot and humid, where things are prone to spoilage, but the only way to ensure that your beans will be top-notch regardless is to buy fresh coffee beans on a regular basis, opting for smaller amounts if you are not a big drinker. The quality of the coffee you brew will improve dramatically if you buy coffee every week or two, versus every month or two, even if you store it properly the whole time.