It has been brilliant. No black on ceilings, not even condensation on windows in the morning. It's not noisy at all, but we can feel 'fresh air' as we go up the stairs. All it looks like is a flat white square on the landing ceiling-it's very unobtrusive. Also the faint damp musty smell which occurred in the bedrooms has disappeared too. I was very sceptical about it but the company offered us a full refund if it didn't work within 6 months. I can't reccommend it enough. I'm just so thrilled that the mould isn't returning!