I stayed in Adam's place for a month, and everything was perfect. The room has a great view of the flowering bush and the street. Although quite small, it had everything I needed, including a full bathroom, a kitchen with hot plate and a multicooker, a fridge and other useful things. It is next to three other rooms with a shared space (there's a washing machine), but I wasn't disturbed by the neighbors and saw them only once. There's a M&S supermarket nearby, and a large Waitrose in a 5 minutes walk (and a bunch of small shops around). Jubilee tube line station Swiss Cottage is just a couple of minutes walk away, Finchley road Metropolitan line station is also quite close (one bus stop).
I should mention some downsides though. There's probably a hospital nearby, and sometimes you can hear ambulances passing by. Also there are some noises from the pipes from time to time, but nothing critical.