Lets start with the positive things: The hostel looks amazing. It has a nice terrace, bar and a pool area. Our room was very small but clean and there was a big closet for our stuff. The staff was also very nice and a big plus for us was the 24h Check-In. The location of the hostel is actually perfect because you are right in the heart of the city.
Here are the negative things: The room was quite loud - especially in the morning when other people were closing their doors it was super loud and we always woke up from the sound. Also our shared bathroom was not clean at all (even though there were not many other guests using it). The bathroom was also quite dark and sometimes the light would turn off just when you were in the shower. Another negative aspect for us was the very very shaky bed (seemed a bit broken).
Overall I would say that the hostel is nice for a few days to explore Lissabon. But if you need more privacy and prefer something super clean think twice.