This is a clean, cute and relaxing place to stay in Lisbon.
It's right next to a park and forest area, so you get very natural views and plenty of song birds while still being in the middle of Lisbon. I'd say it's especially good for longer stays and people who aren't rushing to see as much as possible in only a few days. The metro is close (maybe 10 minutes walk) and it's easy to get anywhere, but it's not right in middle of the tourist zone (which for us was a plus).
We enjoyed our month at Isabels and would glady return.