My husband and I stayed here to kick off our honeymoon, and we couldn't have picked a better location! It is arguably a lot of space for 2 people, and a little more expensive than we could've booked elsewhere in Lisbon, but it was nice to be able to spread out and also to stay right in the heart of Baixa. A Portuguese friend had recommended the neighborhood primarily because it's flat and easy to navigate because the streets are aligned to a grid (unlike the rest of Lisbon which is hilly and has very confusing winding streets), and he was right: it made the start of our trip, when we were super jetlagged, a lot easier.
Aside from the location, we picked this apartment for two reasons: the elevator and the balcony. The elevator definitely came in clutch as we had a lot of luggage for our 2-month trip, even though the apartment is only one story up. To be honest, we didn't actually end up using the balcony. In late October, it can be quite chilly in the mornings, and the position of the balcony at the back of the apartment was such that it doesn't really get direct sunlight, and so it was a little too cold to sit out there. There was also usually a lady in the building opposite hanging her laundry out the window, so it didn't feel especially private. So, even though it is cute, I wouldn't necessarily recommend booking this place for the balcony alone, though it has plenty of other amenities to make it worthwhile.
The apartment has two bedrooms and as a couple we obviously only needed one, but the other bedroom still ended up coming in handy as at one point my husband and I ended up on different sleep schedules thanks to the jet lag (he would wake up around the time I would finally manage to fall asleep), so he would go and lounge in the other bedroom and browse the Internet while I slept. As other reviewers have noted, the WiFi reception in the back bedroom isn't the greatest (it does work but then sometimes randomly cuts out for a while). It's fine in the living room and front bedroom. The downside of the front bedroom is the street noise, especially around midnight when the garbage truck comes by; I would not recommend that room for someone who is a light sleeper.
All the Diva Apartments staff we interacted with were super kind and accommodating, especially letting us check in early since our flight landed around 11am, and also storing our luggage for a few hours after checkout. Since this was our honeymoon, they also left us some extra goodies to make our trip special - much appreciated! Thanks again for everything.