First of all, the place is perfect already for its price-range. Host is very kind and warm person. He is very friendly and helpful. The place is fine for staying over, and if you are spending most of the time outside anyway. It definitely smelled like smoking place when i was there, Im not sure if the guest before me smoked, but for non-smoker this is noticeable.
It is also beside a road, so for someone like me who is used to complete silence night, the sound of some running vehicles late at night woke me up.
My stay in Sintra was enchanting... :) Luis' place is very cheap, good deal for a backpacker, and even for a girl like me!