We spent 2 nights in Kannell's hotel: in fact, if you're seeking for an Airbnb spirit, this is not a place for you (no traveling advices, no brochures, no tips on the must see...). We didn't actually met the host and communication was very formal.
In general, we found the place not really clean. As a matter of fact, we found used cotton swap and band-aid on the floor and in the shower (the place is in fact divided into rooms who all share the same bathroom so we were maybe unlucky with our neighbors). The general state of the flat would need some work to be done: lots of moisture spots in the bathroom and next to the window, walls with marks and dents.
For people who are noise sensitive, you should also know that the flat is located on top of a tube line.
To conclude, if you're only looking for a cheap place to sleep in the center of London, then it might meet your needs.