I bought one a few weeks ago for our new dd who is 3 weeks, it has given me great peace of mind so far as i spent the first few months of ds1 and ds2's life worrying and streesing about them and the risk of SIDS, but someone said they are a waste of money as they dont always work as they should, has anyone used one? did you find them helpful? did they have any problems or faults? Id love to hear what you all think of them! xxx