We had a great time in Lisbon, staying at Guilherme's apartment. It was located close to the metro (3 minutes walk), was easy to find, was secure, and, being at the rear of the building was very quiet, given its central location. The apartment is also very close to the tram 28 terminus (directly across the square). There is a reasonably-sized supermarket on the south side of the square, which we missed initially. The apartment was spotless when we checked in, which is always nice to see. There is no shortage of places to eat nearby, and the prices in Lisbon are very reasonable compared to other European capitals we've visited recently. The only word of caution I'd give is to avoid heading North from Martim Moniz after dark since some of the streets seemed a little less safe, although we had no issues. So, in all, I'd recommend this apartment and would definitely stay there again if returning to Lisbon again in future.