I stayed at Bishop Mountain Hall twice in August, and was very satisfied. My room was very clean on both stays, no complaints there.
A few things I did not like were:
The cafeteria shuts down breakfast at about 9:30 or so.
Rooms on one half of each building housed men, and the other half housed women.
There is NO air conditioning, although the windows open a fair bit.
The last time I was there, I was in McConnell room 436, and there was a bright floodlight that is used to light the field at night that was left on until late one night, even when no one was using the field, and I had to call security to have the lights shut off.
Other than that, I had a very pleasant stay.
I actually thought that this was better than the Crowne Plaza (now the 'Plaza Hotel Montreal'), where I had a horrible experience. It was certainly a $46.01 per night well spent.