The location is very good, but I would suggest more getting there from San Marco rather than Rialto.
It is indeed a walking distance to main attractions and from there one can get further. From San Marco to the airport one should count at least 45-60min.
The apartment is clean, but could be maybe accommodated with a proper sofa sitting. In general there is only a bedroom and kitchen with a table and another bed. Bathroom is fine.
What needs to be fixed better is the WIFI (doesn’t reach beyond the entrance from another apartment), too dishwasher shelf, main apartment doors locking and the bedroom bed which when set for two is a simple combination of two beds put by each other which after an hour of sleeping and moving creates a whole in the middle and beds waving away from each other so one cannot sleep really together, if in a couple.
I would come back to this apartment, because I appreciated the location, the cleanness and communication with hosts.