I booked a room with AB Flatmate last October for 3 months. I found a room on their website, and after visiting the room I booked it with an agent.
It was absolutely not the room of my dreams (kinda small and not perfectly clean) but it was close to a metro station, and it was very important for me.
Anyways I don't give 5 stars because as I said the room was not awesome, but a least it fitted with my budget and and could move in quickly. (The rent was £150 per week, and I moved in 2 days after i visit the room)
I received my deposit back last week, £50 were missing because my roommates and I didn't clean the common areas every week.
I paid £85 for the agency fees, which is correct I think.
Anyways I had a good experience with them even if it was not always perfect.