I was looking for a waterproof case for my iphone that I could easily mount to my bike. I found one and so far I have found it very good.
The case is lightweight and well constructed, I found this reassuring and felt confident when taking the bike out in the rain. The product specs carefully state that it is splash proof - NOT waterproof! It definitely is splash proof! I was out in heavy rain - the only adverse effect was that the screen misted up slightly. But I think you can avoid this. I had closed the case in a warm room before leaving for a ride!
The inner silicone/rubber tray safely holds the phone and creates the seal when the case is closed.
The hinge can detach from the main body, but it is easily reattached with a firm press. This only occurred when the case was open. I found the clip for the hard shell to the mount very good - so much so that it wasn't easy to remove at first.
The only negative I have is that the tension grip mount for the handle bar needs to be a little tighter IMO. It seems that if you tighten it too much the threaded strap jumps the teeth in the screw mechanism. It is tight, but not that tight. I think a fairly rough ride could cause the mount to loosen.