I have 2 of these I got a couple years ago and I just bought two more. While I do think it is a great product, and much cheaper than Thule, etc. I don't know how strongly I trust the locking mechanism. As one person noted the other side is free to spin, but you'd need channel locks or something for that, the real issue is that even when it's locked you can just use the locking mechanism as a lever to loosen the fork mount. There's nothing to keep it from rotating. If there was a third point that could not rotate that it could lock to it would be much less likely to be defeated. In any event, I DO lock it but I also run a cable lock through the frame and rear tire.
One thing I like about this mount compared to any other I could find is that it is steel, so I was able to weld it to a bar on my truck, which I couldn't do with the various aluminum options out there. The other nice thing with the latest version is that they added a little ribbon to release the handle, which you pretty much needed a screwdriver to separate on the older ones.