Well, I just returned from this, and it was great!
It was a little awkward, going down a set of terraced houses, with the usual small front rooms (me thinking: how can you have a gig there?). When I came to the house where the gig was, I couldn't look into the front room as all the curtains were drawn, but I rang the bell, and it was pretty obvious people were expected.
Basically, the gig took place in your bog standard terraced house (with the wall between lounge and dining room taken out, but with a corridor) Not a lot of space therefore, but it snugly fit the audience of 25 or so, plus the act.
The acts were great. The support act (which was the artist I wanted to see), did an acoustic (amplified) solo set. The main act however, was a proper 4 piece band, with drums, base, guitar and vocalist (all amplified). The band alone took up half the lounge
As for the atmosphere/people there: basically it was a party with loads of good-natured people and quality live music.
Seeing this house has gigs every month or so, I think I will go again.