This property worked really well for me and my husband. We used it as a base while we biked, walked and relaxed on the beach in Key Biscayne. Here's some information you may find helpful.
The Apt Building: Could benefit from sprucing up but despite being on the corner of Crandon (the main street) and a street lined with palm trees it was very quiet. All of Key Biscayne is very safe.
The Apt: It was small, neat, tidy, very clean. The bed was very comfortable with room darkening curtains. The kitchen was fine for our basic needs of breakfasts and lunches. There is a tiny pool we never used. There is no outside area to sit privately, which is too bad, and there's no view to speak of. We were there to get out and see the area, so that didn't bother us.
The Beach: It's a 2 block walk to the gate to the beach. You can sit in the sun on the beach or in an area under the Palm trees. There are some Adirondack chairs and tables, very nice, clean restrooms and a shower to clean sand off your feet. This area was not crowded when we were there (early March). Once there was no one else using the area! You can walk the beach both directions. It is a (brisk) 30 minute walk down the beach to the lighthouse.
Location: Walking distance to everything! You are almost in the middle of Key Biscayne. The Winn-Dixie Market is steps away. Three very nice restaurants are across the street. (We especially liked El Gran Inka, Peruvian food). It is 5 blocks to Key Cycling where we rented bikes and biked to Bill Baggs and Crandon State Parks, which I highly recommend.
The Owner: Alejandra was very responsive. I had a few questions before we left and a few when we first got there. She responded quickly, often within minutes, in a very friendly manner.
Summary: If you want a base for exploring the Key Biscayne area this apartment could work nicely for you.