I stayed in Stefania's flat for 2 months whilst on a volunteering placement, and would warmly recommend this as a quiet place to stay for up to 3 people in Thessaloniki.
Location: A quiet suburb very near the city centre, right next to the University of Macedonia. 10 minutes walk down to the port, 20 minutes to the centre/Aristoteleous square. Lots of nearby supermarkets, eateries, hairdressers. Also 5 minutes walk to the national park, a slightly hilly hike with beautiful views at the top.
Transport links: Good bus links within 1-10 minutes walk of the flat. Moovit is a great app to show bus routes, although actual timings may be more flexible than it suggests. 20 minutes bus ride to the train station (17/37), 30 minutes to the airport (01X).
Facilities: Excellent wifi, basic cooking facilities (kettle, hob, oven - no microwave), air con/heating. No washing machine, but there is a laundrette 10 minutes walk away that is 3 Euro per wash.
Other details about the flat: Quiet with little noise disturbance from the road or neighbours. Only very transparent curtains so you may need eye shades for sleep if you are sensitive to light. In the summer it is mainly in the shade so is a nice chilled respite from the sun! Not so good if you want to sunbathe etc.
Recommendations: Falaifel Centre just 10 minutes walk down the main road - super good value fresh food, was a favourite of mine during the stay! Also if you walk uphill to the old city you can have a drink and eat looking out over the whole town and port, beautiful.
Communication: Stefania was very prompt with her responses throughout, check in and out was straight forward - no complaints here.
Overall a lovely place for a chilled stay in Thessaloniki, especially longer term rentals, and Stefania is an excellent host :)