Product review (4 stars): Noticed a difference without one.
After reading some of the reviews I held off ordering a replacement air filter.  After a couple of weeks without a filter in it I started to notice that my ice and food started to take on some of the oders of other foods.  I ordered a replacement and guess what, the oders went away.  Needless to say I will make sure to replace the air filter at least a couple of time a year.