I thought over for long time and decide now to leave a review which is, to my opinion, honest and fair.

Martha is a very nice lady, speaks English pretty well, so that we could communicate without problem. She welcomed me with a big smile and explained me everything.

Now to the accomodation:
Pros:
separate entrance, so I could have a bit more privacy.

Contras:
A. In the room there is NO internet! The WiFi signal is so weak, that you have to go to the kitchen and stand behind the door (wood door), otherwise you don't get internet access there, either. I went to her living room to get internet access, but at night the door from kitchen to living room will be locked, so you don't have access to internet all the time.
B. The toilet is extremely small! The shower is not suitable for me to take shower at all (so I didn't take shower there for 2 days). For me this toilet / shower is in such a bad condition that going to the toilet was a torture for me. I don't know if all Brasilians live like this way. There is no picture of the toilet on Martha's listing, unfortunately.The small small toilet is shared by two rooms.
C. My room is very small, too (I knew it from description before booking). But it is smaller than I even expected. This tiny room doesn't have a door (only curtain). I didn't feel really safe.

I have been to many places of the world. This is the only time that I didn't feel the price (30USD per night) was OK for what I got.

Afterwards I found another place at Maria for a bit more, but it was a much much bigger room with much better value.