We were 7 people who stayed at the apartment and it was quite comfortable :) The underground station "Elephant & Castle" is just a 5 min walk away and very central (near London Eye, Big Ben, Westminster). One of the showers has a very low pressure so make sure if you have long hair, to use the shower in the big bathroom ;) There is also a big fridge, washing machine and a dishwasher. We stayed just for 3 days but it would also be perfect for a longer stay.
Everything was clean and we enjoyed our stay a lot.