Sony T7 - is very new to the market so there is little customer information available. I would not expect it to differ much from the T1, T11, T33.
Biggest complaint has been the very weak flash. It has a range of 5 feet. Picture quality for all the "T" series has been very good.
Nikon S1 is a totally new type of camera for Nikon and these are now getting into the hands of consumers. But it is too early to get a good reading of it yet. Nikon just announce the S2, which is the same as S1 but it is weatherproof. This camera has a flash range of 8.2 feet.
Canon SD400 - (and it SD brothers) has been around long enough to hear from customers and so far, it is good news. Many magazines are giving this camera a high rating. It has a flash range of 11.2 feet. The SD500 has a flash range of 16.4 feet.
I am looking to purchase a new digital camera. I am looking for a thin, compact camera. These are the camera's that I am interested in: Sony DSC-T7, Nikon Coolpix S1 or Canon SD400. Any advice and past experiences with any of these camera's would be very helpful.