The flat seemed smaller than the pictures appeared. I think it would be very crowded for 8 people. We were 6, which was fine.
Be careful of additional fees. Our cleaning fee was $120 USD. And then if you check in later in the day, there's another fee, and if you leave any garbage there's a fee.
We didn't have any trouble with the downstairs neighbor, but we tend to go to bed early.
The kitchen is very small and simple.
Overall our stay was fine, but if you have the luxury to look around before booking, you might want to do some more searching. Of course, Venice is overpriced and crowded in the summer, no matter what. (I recommend Verona)