I have one, or an NcStar very close to it rather, and for what you pay, they're amazing.
Having said that, the clicks aren't very repeatable, and there's some lack of clarity at high power.
My wife has shot a 900 yard competition with one on a Rem 700P and it not only survived, but kept right up with my Leupold MkIV, so again, for what you pay....