I stayed at Marta's in a group of four but we did not all arrive together. Two of us arrived just fine while the other two got significantly lost-- on our own behalf, not Marta's-- little did I know I had a set of flawless directions to her home waiting for me in my email inbox. Suffice it to say, Marta's home was wonderful. It is exactly as she describes it in her bio. She is very kind, reasonable, and has a very (humorously) sensible knowledge about Amsterdam.
Her home IS in North Amsterdam but it is very quick and cheap to get to by bus every day or night. We got all around town just fine.
Overall, the group in its entirety had a great experience with both Marta and the town!