We stayed 5 nights in Venice - 3 couples - and it was great. The location is in a quieter spot (which we preferred - if you've never been to Venice before, San Marco in August is unbelievably packed with people) so staying in San Polo was a quick walk away but we also had some peace and quiet at night!
Venice in general is pricier than many places in Italy so this value is great. There are plenty of cafes and restaurants nearby and even a few shops and gelato stops. There's a water taxi only about a minute walk away that will take you over the Grand Canal so you can get to St. Mark's Square easily.
The place is clean and has a good amount of space. We felt safe in the area as well.
Just an FYI not a reflection of this AirBNB (because we loved it):
We had some confusion around disposal of trash - if you are not used to Venice disposal and recycling practices you may want to read up on it. There are specific days and times you can dispose of certain things but you must be home when the collectors come around or make sure to be at the garbage barge on time (one 2-hour window per week). If you don't dispose of your trash appropriately then the cleaning staff has to take it home with them and dispose of it during their designated times. I imagine this is true with any AirBnb in Venice so just keep it in mind!