The room was ok but it got so hot at night, and if you opened the windows the room would be swarmed with mosquitoes in minutes. There are also two heaters in the room but no air conditioner? The shower was small and a little dirty, and all the dishes were very dirty, I had to wash all of them before I could use them. The walls are decently thick, but the doorways let so much noise in, I was woken up at 4am buy people getting ready to leave, and pretty regularly woke up to people moving around outside my room because of the noise
The location was close to the train station, but the train drops you off in a pretty inconvenient location within Venice, and if you want to take any of the boats as well as the train you should buy the day pass for transit which is 20 euros. Looking back, booking a place that was 40 euros more expensive for me and my girlfriend in a better location might have been worth it.
All in all, the room isn’t terrible and if you can’t afford to stay in Venice everything will definitely be cheaper in Mestre. I wouldn’t tell someone not to stay here, just don’t expect much. Do your research and maybe stay in Venice instead.