We booked well ahead and got two rooms including breakfast for £99 each a night, which is good value for central London on a bank holiday weekend. The rooms were furnished to a good modern hotel standard and were comfortable and very clean, with en suite shower rooms. Some things to be aware of (should these things be important to you), there's no air conditioning but the rooms have fans; the rooms are smaller than you will be used to if your experience is of big American hotel rooms, but big enough for all normal purposes (and you have the whole of London outside the door, what are you doing skulking in your hotel room?); if you're at the back of the old block your view will be of the new annexe (see previous point about all of London).
The service was very friendly and helpful. We followed others' recommendations to ring reception after we booked to request rooms in the old buildings at the rear and the hotel gave us what we asked for. However, the square it's located in was quiet and I'm sure rooms at the front would have been fine. It's a listed building and so there are no lifts and for this reason I would advise asking for rooms no higher than the second floor. If you have mobility problems they have bedrooms on the ground floor.
Breakfast (or brunch at the weekends, which goes on to a very civilised 2pm) is in the refectory of Goodenough College, which means going out into the square and in through the quad. This was a rather nice way to start the day and breakfast was good and very plentiful. We didn't have time to explore the bar, which is also in the college, or the private garden at the back of the Club.
The location's great, it's a £6 taxi ride from Euston, £10 taxi ride to the West End and Russell Square tube is 10 minutes walk. You can walk to the British Museum and you're also very close to the Brunswick Centre, which is unlovely but has a range of useful shops for all the stuff you've forgotten to bring with you.
Summary
Customer Service
Quality of Room
Quality of Food
Cleanliness of Hotel
Value for Money
Family Friendly