That was our second time staying at that place. Same as first time (a year ago) - Perfect.
One important thing to note (if you are not very familiar with London) is that if you are using the Uber app or Apple maps, be sure to search for "SE1 9ET" (it's sort of like a very precise zipcode in the address). There are a few places called Park Street and you want the right one. Also 71 in the address refers to the actual apartment number. I mean the address of let's say 67 Park Street would be the adjacent apartment in the same building on the same stairwell landing.
We were in London just for a fencing competition, so we didn't have time to do much sightseeing and we used Uber to get around, but I did notice that there was a Subway (underground) station 5 (at most) min away walking. Also there is a convenience store open very late about 5 min away (Londis) where you can get bottled water, alcohol, etc.
In general, the area is fun to walk around. Same as last year, we ate breakfast at Pret-A-Manger (1 min walk) and dinner at Bill's right in front of Pret-A-Manger. Note, there is a flight of stairs once you enter the building and another one inside the apartment immediately past the front door to get up to the living room. It's kind of narrow for carrying large suitcases. Just something to note, wasn't an issue for us at all, though. The apartment is pretty close to a lively area (Vinepolis at Borough's Market) with plenty of pubs there but it's quiet inside the apartment. There are two bedrooms on the main (living room) level (remember that level is up a flight of stairs once you enter the apartment) and a loft up the stair from the living room. The loft has a bed but no door and the ceilings are pretty low - I do not think you can really stand up in there. Also the stairs up to the loft are really narrow and steep - getting up/down requires lots of caution. I do not suggest kids stay up there. We did not use the loft neither last time nor this time. One of us just slept on the couch in the living room. The second bedroom is kind of more like an office with a twin-size bed, and the doors to it are folding doors that don't close tight. It was not an issue for us, but if you plan to stay there as two/three couples/families, it could be an issue because really only one person can comfortably stay in the second bedroom. The first bedroom is regular-sized and has a queen bed. The loft upstairs has a full-size mattress and a couch (but again no door and hard to get up/down the steep stairs). The bathroom is a hallway (i.e. not inside one of the bedrooms - so it can be shared by all guests easily) and is clean and totally fine otherwise. Water pressure and temperature are both good. The kitchen is modern and is part of the living room. We did not do any cooking though. The place could use a little bit of minor maintenance to replace burnt out light bulbs and it does appear larger in the photos than in reality, but it all worked perfectly for us. We have stayed there twice and it will be our place of choice again if we come back to London next year.