This place is amazing. We were a family of 5 and we found the apartment very comfortable and spacious. The location is perfect and you’ll find an amazing juice bar and a variety of cafes as well as a supermarket in close proximity. There’s also a Mc Donalds that’s 4 minutes away.
In Venice everything is walkable, so I’d say Rialto is around 8 minutes away while St Mark’s would be around 12-13 minutes away.
If you’re arriving to the apartment with less baggage from the Santa Lucia station, I’d recommend you walk instead of taking the water taxi which costs 7.50 per person each way. The station is just a kilometre away and it would take you around 13-14 minutes to get to the apartment. Just make sure you have proper directions before hand though!