REI - short for Recreational Equipment Incorporated - actually describes them pretty well. They are generalists in outdoor sports equipment offering anything from mountain climbing and camping gear to rafting to hiking and camping equipment. REI has a reputation for quality, and the binoculars and spotting scopes they sell are from quality brands and likely selected for durability.
REI does not sell gun scopes or other hunting optics, but does focus on binoculars and offers a few spotting scopes. We are surprised they do not have any night vision products. Most of the binoculars that REI carries are great for hiking, bird watching, and general observation. Wisely, most binoculars are water proof.
If REI carries the optics product you want to buy, we would definitely recommend them as a quality retailer that will likely stand behind their products. However, we have not purchased binoculars from either an REI store or REI.com, so cannot give a direct review as of yet. If you have bought optics from REI, please leave a review and let the community know how they did.