If you wanna explore Lisbon by walking, it's THE place to stay: the location is absolutely perfect. The hosts were super clear in their explanation, very responsive, even at late hours. The place is small, true, but excessively clean and convenient.
The only neg point is if you're used to double glazing, both for heat (we travelled end of November) and noise, you might find it complicated sometimes: garbage collection comes by every night not too far of, and you might find it loud.
It really wasn't an issue for us as everything else - especially all the things our hosts could act on - was absolutely on point.