Oodles of character in an excellent location! It's great being on the stairs (no road traffic), and it's close to everything from bakeries to restaurants to attractions. Living room at the front is great, windows onto the stairs are brilliant, bedrooms both are adequate size and fine for sleeping.
COVID probably set all hosts everywhere back a bit, and there were a few maintenance items that were somewhere between quirky and frustrating, but those will probably all have been fixed long before you get there, and they did not spoil our stay. The weather was moderately warm when we were there, and the windows make everything very pleasant. If you are not good with heat this might not be the best place for you if it's properly hot (not everywhere has air conditioning, this apartment doesn't, but doesn't need it if it's only in high 20s).
If you are booking (and you should) then note you will need access to your Airbnb account to check in - the code is only supplied there, and only after check-in time. This was tricky for us because we had different people traveling from different directions, and the party that arrived first could not get the code. This is likely only a problem for those traveling from outside Europe who may not have cell data, especially when they first arrive.
All in all we had an excellent experience in Lisbon. There are fancier places - we stayed in another after this in Porto which was lovely - but that one was also double the price. This may be exactly what you need, and we can strongly recommend it.