The other reviewers are correct about the positives- this is a great location, you can walk straight down the road into the City, using the Gerkin as your guide, and be on London Bridge in 20 minutes (there are also several tube stations within a few-minutes' walk, bus stops right there, etc.). There are plenty of clubs and take-away places and restaurants in close proximity, as well as a Tesco Express, etc. One nice added feature is that the TV has normal cable but also Netflix enabled. Check-in and -out was very convenient and efficient.
The other reviews are also correct about the negatives. Even on Sunday and Monday morning, the music in the club 2 floors down comes on at 7am. Personally for me, it's not loud enough to wake me or prevent me falling asleep, but it is definitely noticeable, so might be a problem if you're used to real quiet. There is also the train (the overground line) that goes by very regularly. The place itself is a "studio" apartment, but really very small, no bigger than a typical hotel suite. It was somewhat too small for a family of 4 for 4 days, but we managed since the weather was nice and we could be out exploring all day. There was ample space and utensils for snacking or sandwich-making (bar fridge, etc.), but it would not be easy to cook full meals from scratch, if that was your aim.
There were two "temporary" things that soured the experience for us, I did not deduct a star because they may not be the host's fault: we had no wireless for one entire day when trying to get transportation and book hotels for the next leg of our journey. Being non-English, we didn't like having to use exorbitant roaming fees for data. This was the fault of the service provider but was certainly inconvenient. Secondly, the temperature controller on the shower was sticking and slipping - i.e. not engaging the actual plumbing just the handle slipping around uselessly, if you could get it to turn at all. As a result, the shower was full-blast hot water the whole time. I will say that there is certainly ample pressure and hot water available in the shower! Too much of it for comfort without the controller working. Again, presumably these are short-term issues, and if we didn't have them it would be a 4-star stay (for the cost and location), but our experience (including these issues) was 3-star.