I've just got an SJ4000 WiFi, cost just under £80 with a full set of mounts and 2 batteries. Reason i went for it over a GoPro was because for an equivalent price GoPro, you can't change the battery (if you are out and about and its runs out) and also due to the lack of screen. I'm going skiing in 2 weeks so will give it a good try out then. I wanted a screen because if I go skiing and it isn't quite set up at the right angle, I wouldn't know until I get home and would be a bit annoyed if I had spent the whole week filming the sky......
With regards to the mounts, if you give the joints where they attach together a rub with some wet and dry paper it give it a much better key and hold together a lot better. All the GoPro mounts fit it anyway if you wanted to buy those instead. It films 1080p at 30fps and 720p at 60fps
I might not use it a lot and didn't want to spend £xxx on a GoPro to sit in the drawer. When compared to the equivalent GoPro it was a no brainer for me