This is a great hostel! I would say the only downsides are 1) there are only 3 showers and 2 toilets and 2) if you're assigned one of the top bunks (the bunk beds are three beds high) you may be scared of falling because there is no railing whatsoever and its pretty high. Other than that, it has a cool atmosphere, hip young staff, you can order lots of different drinks at the front desk all day, the wifi is good, and everyone I met there was cool. Good location too!
Nomad was great! Instead of having a bathroom with lots of shower stalls, each bathroom only has one shower so you have privacy and it's clean. Beds were clean, there are lockers in the rooms and they give you a key for yours, the staff was friendly and helpful, and breakfast was free. I definitely recommend it.
This hostel actually is not in Venice itself - it's in a village called Tessera, about a 20 minute bus ride from the city. If you don't mind that, this is a good hostel: run by a sweet and friendly guy, it basically feels like staying in a house. My friend and I had booked a 4 bed mixed dorm but ended up having the room all to ourselves and paying the same price. And the beds are REALLY comfortable!