I was very happy with most of the amenities.at the Club Quarters Covent Garden Holborn, but I can't say I would return immediately...
PRO : Location, lovely neighborhood, near the Holborn tube station, great restaurants, easy walk into downtown London, quiet at night, across from a beautiful park.
The bed and shower were both amazing. And one of the staff (Odette) was as delightful as one could wish - solved any and all problems with a smile.
CON : I watched (and experienced) several customers be treated with disdain by a different member of the staff, and not because the customer was demanding anything unusual - rather the staff member seemed irritated to do his job ?!? Despite all of the PROS, my feeling about that one employee might cause me to look elsewhere on my next London trip.
Also, the fridge and microwave (in the room) were not working properly - not a huge problem, but annoying.
OVERALL : Many things to recommend, and one or two less than stellar moments.