Oáza is dining room/canteen - there is just two chairs and one table (mostly old people sit on this chairs), other eat in the desk across the whole place and need to be standing while eating. But there is no problem to take the food with you and eat it in nearby park for example.
The food is very cheap, so it's possible to eat here every day for working people or students (that's why this place is crowded around 12-1 pm).
I always enjoyed my dish - it's normal cuisine (I personaly also use frozen vegetable or vegetable from tin when cooking at home), I think the taste of the food is great - I wouldn't be able to cook it better, so I was always perfectly satisfied.
Don't be scared of the place and go there :)
Updated from previous review on Tuesday July 22, 2014
Cons: no place to sit