We've spent 4 nights at Rossella's appartment and overall it was a great stay.
Pros: location (quite area, very close to Rialto bridge and east accesibility to San Marco and train station), size of the space(large enough and intimate for 4 persons), quite modern and had a lot of amenities (everything you need to feel like home)

Cons: unfortunatelly the main bathroom doesn't have a window so it is purely ventilated and it has a particular smell. So we bought something to make it smell better. one other thing we would have needed was an extra key (we were two couples and didn't have the same program, so we had to make the others were home)

As I said the experience was nice and I really appreciated the flexible check in/check out. I would gladly recommand it.