Just got it yesterday, extremely stable for overclocking, pulls up about 600 mhas/s for now.
According to this info Robi has shared, should be able to get about 700 with a bit of work.

Word of caution, if you go Asus model like I did, make sure you have sufficient number of power cables. Only 1 8 pin cable comes in the box and 2 are required to power the card. If your PSU is older, like mine, consider getting additional cable.