Prices are just about equal on Huobi, Stamp, and Okcoin right now... That doesn't happen all that often
The other exchanges have seemed at times like they want to take off but the market is being nailed down by Wall Guy on Stamp. There was a wall yesterday 1500BTC strong at $670. Last time I checked today before I went out, there was a wall at $665 of over 1000 BTC; now that I have come back, that wall is sitting at $660. I guess it will keep advancing on the retreating Bid wall until it retreats no more.
$650 broke as I am typing. Good! I bought at $660 but the market needs shifting.