My stay at Marsha's place was very good, with just one small drawback. The flat is really well located and you get a lot of space (and nice kitchen facilities) for the price. She works with hostmaker, which makes check in easy (and kudos to her for dealing with my late night check in after a late landing at Heathrow). Finchley road is a great area, with good transport links and all the shops you need to cook your own meals around, and I enjoyed being in that area.
The one drawback for me was that there was something in the flat that really bothered my allergies. I don't think the flat was unclean, but it was an older building and I can be quite sensitive. So just something to keep in mind if you are looking to book and have allergies like I do!