Overall a good product. Has a nice, smooth feel, similar to a Bigsby but much simpler and more discreet and stays in tune well. Fitting is simple and doesn't require any alteration to the guitar.
There are one or two design problems though. Firstly the nut that adjusts the tension of the arm, so that it either swings away when you let go of it or stays where it is, is very hard to access without taking off the guitar strings and dismantling the entire unit. Also, because of the nature of the spring position, the tension of the arm is not consistent throughout its movement and its hard to get it exactly how I want it.
Secondly, the arm is held at the correct angle by a small grub screw which needs to be tightened almost to breaking point to stop the arm twisting in its socket under use.
Thirdly, with the arm attached my Les Paul no longer fits in its case and there is no simple way to make it fit without completely dismantling the unit unlike a Floyd Rose etc. where all you have to do is unscrew the arm.
If the manufacturer could address at least the first two of these problems (which shouldn't be too difficult) this would be a five star product.
Overall, this sounds negative but once you get it setup properly it works well and I'd still take it over a Bigsby.