Yea, very nice spot and very well protected. Can be very busy on weekends. No services, but free. Elliott Key (a couple miles south) should be a decent harbor once the NPS finishes the reconstruction project. (Reconstruction may already be completed - I don't know.)
I lived in a house trailer at Eliott Key for about a year during my assignment to Biscayne National Park in 1973/1974. Great place, but mosquito Heaven! Some entomologists at Univ of Souh Florida had us collecting mosquitoes for "research." Every other day we'd change-out the three gallon(?) glass jar beneath the trap with a new jar. ...we never ran out of mosquitoes! I vaguely recall the professor telling us they'd identified 52 different specie of mosquitoes. (Can't guarantee the 52 specie figure [that memory has somewhat dimmed over time], but it was a S***Pot full of mosquitoes!)
...if you go to either place, just remember the DEET !
Best,
C&M