works just fine. a bit of ghosting but nothing that would make me want to buy a real one.
I got mine from DX:
http://www.dealextreme.com/details.dx/sku.21959
the dot is incredibly small compared to my aimpoint and other RDS.
the only real issue is that the rail mount is where the switch is attached so you cannot mount this clone directly onto a pistol slide, by removing the rail mount, which I had thoughts of doing. it's now on my MP5 or gets swapped over to my m500.