I stayed in Nadia's for one solid week, over Xmas period. I found the apartment very clean, spacious, furnished with taste, private and with very good Wi-Fi connection. All essential amenities were provided and functional. Laundry service was available paying a reasonable extra.
Only on a slightly less positive note is the nearby construction site that can be quite noisy in the morning, but not really too much hassle.
The location is excellent to access the Slipway complex, where one gets sea view restaurants, SPA, salons and several shops for souvenirs. The jetty is also at walking distance and boat trips to nearby islands are available and easy to access. Tuk tuks are parked just outside the complex parking lot and available 24/7.
Nadia wasn't around during my stay, but provided me her personal cell number to contact in case of issues. Anyway, the nearby Slipway hotel personnel was always available to help if necessary (e.g. they received my lost luggage from the airport on Xmas day, while I was at the beach!).
Overall, I found Nadia's place a very convenient base to discover Dar es Salaam and would definitely return here with pleasure.