The location is fantastic - Chiado is in the middle of everything! The apartment is impeccably decorated (Ricardo, the owner, is a designer) and has everything you'll need for a short stay - pod espresso machine, fridge, oven & microwave, etc. Also a few of Lisbon guidebooks - we liked the Rick Steves one and used it a bunch.
Also, the apartment sits on top of a delicious Italian restaurant, highly recommend trying that... you won't be able to resist as you'll smell it every time you come & go.
Only complaint is the place smells of mold fairly strongly. Lisbon had some HEAVY rain just before we arrived (enough to cause flooding all over the city) so it may have been from that.