Isabel's has a small and cute apartment in one of the nicest areas in Lisbon. There's a bunch of awesome cafes and restaurants around the apartment. The place was clean, and the host was very responsive throughout our stay.
One thing that kind of caught us off guard is that there is only enough hot water to last 10-15min in the shower (you will need to wait for it to be reheated afterwards), and so you'd want to watch out if you're a couple showering back to back. It's not a major issue though, and I can definitely recommend staying at Isabel's if you find yourself in Lisbon.