Perfect for a one or two night stop. Kypseli is a bit down at heel as a district, but it's safe and there are excellent eating opportunities at St George's Square. 12 minutes walk from Viktoria Metro, so you can get to the airport in about 90 minutes with a change at Monasteraki.
Rooms are simple, functional and clean. Bed is super comfortable, especially if you prefer a soft mattress. Everything is pin code operated for access after 9 pm so can't comment on staff.
Very good value.