I was visiting London for business (trade show in ExCeL). The apartment was clean and very nice. Perfect when traveling with a colleague, as there are not only two bedrooms, but two separate bathrooms as well. Travelling to London ExCeL was no problem with public transport, it took me about 20-25 minutes to get there. You can find a supermarket and a good restaurant within walking distance from the apartment.
I am not sure if I would feel safe at the DLR station very late in the evening. The latest I was there was around 9PM and that was fine, there were still enough people on the street and I did not feel uncomfortable.