Gargyno,
Just for the record, what kind of tobacco will you be curing in there? In Conn., (I worked for professional growers,) we have 2 kinds of tobacco, basically--air cured and fire cured. The same sheds are used for both.
Depending on what kind of tobacco you're curing will determine what you want the shed to be able to provide. It looks OK for air curing and even for fire curing, where you have stoves or fires on the floor. (We used charcoal briquettes before switching to propane to cure shade tobacco in the 1960s.) The tobacco needs to be at least 6 feet above any fires, preferably 10 feet.
As long as you can increase or decrease humidity with your shed it should be OK. We used to rake the dirt floors of sheds before curing to eliminate mold. A plastic floor won't permit fire. Do you live in a temperate or a semi-tropical climate?
Even air cured tobacco might need to be fired at some point if humidity gets too high--like if it rains for days at a time. Your shed resembles those small thatched roof partly open curing buildings in Central America. Conversely, if the weather is very dry for a spell, you will need to close it up tight and conserve the humidity inside.
Too much dry weather is worse than too much wet. At least high humidity can be controlled by artificial heat, but excessive dryness will not permit a proper progression of colors as it cures. For the first few days I would seal that rig up tight, bottoms too. Then, as the tobacco fades to lime and yellow, open up gradually to let fresh air in.
A lot depends on your tobacco type and your climate.
Charlie