I greatly enjoyed my stay at FromScratch! Although I didn't interact much with the staff (I was mostly only in my room to sleep and out all day), they were very kind and always saw me off in the morning with an "いってらっしゃい!".
The hostel itself is a great value, especially considering the amenities (WiFi, showers, laundry, AC) and how clean and well-maintained everything is. The beds are a bit stiff by Western standards, but you get used to it pretty fast. The location is also excellent - only a few minutes' walk away from Sumiyoshi station (access to the Shinjuku and Hanzomon lines), and right next door to a 7-11!
I highly recommend staying here.