I love this thing. One problem that was specific to mine, however, was that the black inner thru axle core got loose and starting slipping around inside the yellow U part of the adapter so much that it actually slid apart. I just super glued it back in. Works fine now. Also, if you have a compression adjustment knob on the bottom of your Lefty like mine, you have to be careful how you mount it to the bike because the design doesn't allow for quite enough room to mount the adapter directly inline with the shock. It interferes with the compression adjustment knob that way.
Aside from my small quibbles with this product, I've had mine a long time and love it. Worked perfectly with my rack.