It may be a bit hard to reach the place if you don't have a GPS map. However, if you know where you're going it would take 10-15 mins from the train station to the apartment.
The area is quiet, close to some cheaper restaurants. It may take you 20-30 mins to reach San Marco square. While the place is not super central, that's not really an issue. If it's your first time in Venice, you won't mind walking around.
The room was clean, bed was big and comfy. You'll have your own bathroom, which is super nice. The room looks better than the pictures. Working WiFi - not super fast, but unless you download something big won't be a problem.
However, the floor is marbel. So you may be a bit cold if you're there during the winter.
Breakfast includes coffee, tea, juice, croissants, bread + jam. Also, cornflakes and oats.
Marco is super friendly and would help you with any requests you may have.
Only issues you may have:
1) trouble fiding the place - though I guess that applies for 90% of the AirBnB places in Venice.
2) be a bit cold during the winter - not really a huge issue, depends how warm you like your room.