Looking at this kind of before-and-after is a good way to get depressed. The transformation of 561 11th Street was noticed and mused upon by the blog Save The Slope:

We have no idea if the new building is great architecture or not. Personally we prefer the old building. One wonders, though, what has really been gained in this process? The new building is not dramatically larger than the old one. The old building could have been a 1- or 2-family; the new building appears to be a 3-family. Perhaps we have managed to squeeze another couple of people into Park Slope, which is great. Probably someone has made a lot of money in this transaction, or hopes to. But the one certainty is that we have lost a bit more of Park Slope’s historic fabric and unique “sense of place”.

Bummer.
11th Street: Another One Bites the Dust [Save The Slope] GMAP