The design is good and the product looks like it will do the job well. The modular design is useful as you can adjust it for your needs/shed etc.

My main problem is that the shear nuts won't shear. The cause seems to be is that these nuts are designed for clamping over metal and not soft wood as used on most sheds. What results is that the connection will crush the wood long before the nut shears. As mentioned in other comments this can be addressed by taking a hacksaw to the nut but this is additional installation and not really ideal. I feel that a spreader bar or large plate washer on the outside may help combat this but this is not included. It was also supplied with 8 nuts&bolts where you need 11 to install with all holes bolted. I had spares that I've used but would prefer to get enough supplied to fit it fully

[Pragmasis Comment: The shear nuts are normally fine but it does depend on the quality of the cladding on the outside of the shed. I'd guess that at least 95% are fine, but the instructions do suggest weakening the nut with a hacksaw, as you've said, if the wood isn't up to it. A spreader bar wouldn't work because many sheds have feather-edge boards, which don't present a flat surface on the outside, and large washers would also not work in that case, as well as compromising the grip that the square section under the coach bolt head provides into the wood, so the whole bolt would be liable to spin when being tightened. You only need 7 or 8 bolts to fit the Shed Shackle sufficiently. There are more holes in the metalwork to give more versatility for how you fit it, but it is not necessary to put bolts through every hole to get it secure. That would just make for more holes in the woodwork for no benefit. The instructions do explain this, with the particular note that the main 'shackle' section should always be bolted through all 4 of its holes. I hope that explains further. We are happy to answer queries.]