Really good but walls are paper thin so you will hear every word from neighbors and only salt water available. Big plus from drinking water station and actually working AC!
I had a good time at Casavia Siargao. The location is ideal if you want to surf at Cloud9: you can walk there in 5 minutes, and it's much quieter than General Luna but still close enough if you want to spend the night eating/partying there. The private room was pretty nice and spacious, with a comfortable bed. The bathroom could use some love, but still it was ok.
The staff is nice and always willing to help, and the hostel has several social nights organised via a Whatsapp group. While I didn't take part in those events, it's a convenient way to meet other travellers.
My only remark was about the noise: my room was facing the upstairs social area and, despite the signs specifying the quiet time (22pm onwards) and also a 500PHP fine for people not respecting it, every night I had people making phone calls, playing the guitar or shouting loudly after midnight (or later) in front of my room and there was nobody around to remind to keep the voice down. That was annoying.
After over 2 weeks stay would say this hostel had dirty toilets and weekend parties + full of young party animal adults.
Great place when you are young and like to party but definitely not for relaxing surf holiday place. Toilet are on young dirty men usage who pee on toilets seats ect...