This was not the best guest house I have ever stayed in, for sure. The room had an unpleasant odour and there were damp patches on several walls. Fittings were not pristine either. Perhaps most problematic was the security light that was on all night and streaming through the (unlined) curtains. Towels and bedding were provided and were clean and the lady who greeted me was friendly.
I was here multiple times (last time from late May to beginning of June) because it is nice and affordable. The sizes of the rooms vary - so check which one you book! - but they are absolutely fine by hotel room standards. I only had ones with private bathroom (and I think in Lonsdale they all have a private bathroom). Service is available 2 houses further at Oyo Lina, where they also simple but nice breakfast. If you arrive at night, they have a key locker and you will be instructed how to get your keys. Definitely not luxury (no AC - but you that is rare and rarely needed in Oxford anyway), but certainly good hotel standards which soap and everything provided + nice staff, so I can recommend it for non-luxury travlers.
Staff was very friendly and the room was clean, however the condition was poor with worn furniture that had seen its best days. The single room I booked was advertised with a private bathroom (not en-suite), however it was used by other guests in the house as well. Some of the few sockets in the room did not work.