Obviously I didn’t have the time yet to test one, but there are some resources on the Web which describe their experience with it. For instance Rob Fowler left a comment on the SONOFFs Banggood page:
This is a very well designed board. The tracks protecting the high voltage are wide and properly milled. The GPIO0 is on a button and the serial pins are run to the edge ready for a header. The layout is one of the best I have seen for ages in a 220V product, seeming to choose safety over size. Mine is already running micropython and I also tested LUA. I can see a use for 100s of these.
Brian Moses got the chance to pre-test one as a early peak and seems quite happy about it (read more on this blog). Also Pete Scargill has already received one and wrote a blog post about it (find out more here). And last but not least ITead Studio has started a Indiegogo campain for this product.
For completeness I should also mention that there is a second kind of appliance from ITead Studio which is called the Slampher. It is has an E27 socket and can plug in one on the other end. Like the SONOFF it can be controlled through WiFi to switch lamps in your house. And to make things more confusing there are versions of the both SONOFF and Slampher which also have an 433MHz RF interface and can be controlled with a small remote control.
Summary: if the SONOFF is relatively easy to program then USD $5-9 for one is a very attractive price for such a device and could enable you to turn your home automation dreams in a price-worthy reality! Now I’ll have to wait until the postman brings me one for testing!
A ridiculous amount of coffee was consumed in the process of building this project. Add some fuel if you'd like to keep me going!