What a lovely house! While you're not right on the beach, you have a great view just above Boulders Beach and it takes less than 5 minutes to walk there. FYI - Boulders Beach costs 75 rand/adult and 35 rand/child.
The house is so lovely and cozy and beautifully decorated. I would be nervous having so many lovely things in a rental but we appreciated them. There is a lovely private patio space behind the house and a wonderful airy patio on the front from which you can see Boulders Beach. The outdoor shower off the patio is helpful to get the sand off before you go into the house.
We would have benefited from a rental car but managed to get around by Uber just fine (we visited Somerset West and Stellenbosch as well as the gorgeous Cape Point National Park). It takes a bit longer to get an Uber as the wifi/mobile data service in Simonstown seems a bit spotty but it does work. We also would've benefited from a local SIM card but were able to navigate well enough using Wifi and our Kenyan SIM card.
We highly recommend this house. Its much roomier than it looks in the picture (though still cozy) and is just such a pleasure to be in. Boulders Beach and the penguins are magical and there were at least two very good restaurants within easy walking distance of the house (Boulders Restaurant and Seaforth).
FYI -- if you're planning to cook, you should know that there are no real grocery stores in Simonstown, just convenience stores. You should get what you need in Fish Hoek or Noordhoek.