Smile has the best location any hostel could have. 5 minutes from Kremlin and on the main street. The rooms are city based themes and I stayed in the Havana room.
There is only one men and one women bathroom for the entire hostel. Also, the hostel charges 50 rubles to keep your bag after checkout (Nothing wrong in doing it. But, guests get delighted if it is free. And it is a general practice in other hostels).
However, the location makes up for all the cons the hostel has. Highly recommended.