We can't say enough good things about Lucy & Martin's place! We stayed with our four kids for several days - the apartment is exactly as it looks and is described - an amazing home to stay in that is only a 1 minute walk to the square! (The kids absolutely loved the place). There's a convenience store across the street, and a coffee place, a bagel place, an ice cream place, and pizza all within eyesight of the apartment, plus the cafes and restaurants on the square!
One note on transportation; if you are driving, be sure to reserve a parking garage (like Mr. Parkit) in advance. Be careful which one you choose - because of the traffic patterns, some may be a close walk (like 5 minutes away), but a far drive (like 15 minutes to drive and park). We used the closest one, and just carried our bags over the five minute walk.
We will absolutely be back to stay here again!