Glaros is a lovely spot and facility, and located at probably the best beach in Santorini for swimming. You can get FAR more for your money here than staying in Oia or Fira, where you might stay if you don't mind traveling to get to the beach, or perhaps if you prefer the charming winding streets, shops, and stunning views of the architecture and caldera to a swimming beach AND if you don't mind spending a ridiculous amount of money to do that. At Glaros, you are just a stone's throw from the beach, which you can see from the outdoor eating area and mini-kitchen (which are great to have!), and most of the units have a view from their outdoor table areas/"porch.". At Glaros you can make day trips for the non-beach parts of your vacation in Oia and Fira, and of course the day hike between the two (allow 5 hrs for getting lost and taking pics, not the 2.5 non-stop time estimate).
BUT MOST OF ALL, IRENE IS AN AMAZING HOST. She goes way out of her way, above and beyond. She is easy going, friendly, and extremely generous. Upon arrival, she'll sit down with you and a map and tell you all the key highlights to consider visiting/doing on the island, including a place for the "best sunset view" restaurant and wine, (which is NOT in Oia). She also told me where I could buy fish from a local fisherman in Emporio, who brings it in fresh every morning. When I managed to squirt ink all over my white shirt from my adventure cooking squid for the first time, which was impossible to get out of my white SPF shirt, she insisted on trying and came back an hour later (at 10 pm!) having found a trick to do it on google and scrubbing away at it. I was astounded, not only that she succeeded, but that she did it in the first place. She also put some olive oil in the kitchen, which was SO nice and helpful. She made my trip on Santorini, and I cannot recommend her and Glaros Seaside enough.