I bought this to try out time lapse photography, but didn't feel I could justify spending out on a Canon unit considering this was a try out.
Unlike the experience of a previous reviewer, the unit sent did fit my Canon 7D OK and worked fine.
Build quality is OK and the fact it doesn't have an off switch doesn't seem much of a problem as long as you don't leave it in it's 'ready state'. Either way a couple of replacement AAA batteries is no real hardship.
I did have one glitch, which I think is most likely the camera. When I selected that the camera should turn itself off after a minute, I found it would only power down after two minutes. This means the camera will stay on if the interval selected is less than two minutes, which does degrade resilience of how long you can keep going on a standard battery. (Still managed 8 hours of shooting though)
However if the interval is greater than two minutes, no problem as the camera powers down, greatly increasing endurance. I also set the camera so that it doesn't display at all on the rear LCD display, which also helps battery life.
Anyway, if you want to have a dabble with time lapse and don't fancy lashing out for Canon original equipment. I think this is a good deal.