Sonny's place has a great location - just about a 7 minute walk to King's Cross station and near stores and restaurants. A few minutes more walking gets you to the British Library. The area seemed safe and is well lit.
The apartment is small but had plenty of space for 3 of us to stay comfortably - you are not going to throw parties or have lots of guests here though. The kitchen was well equipped and easy to cook meals in. The deck/terrace outside of the back bedroom was a lovely place to sit for morning coffee and reading.
The only issue some people may have is that the front bedroom is somewhat noisy throughout the night - it overlooks the main street. City people shouldn't have a problem with the noise but if you are used to sleeping in silence, take one of the back bedrooms - they are very quiet.
Sonny was very responsive and got back to us quickly whenever we had any questions.