Also please vote if you would like to use Coinbase or not for storing large amounts of bitcoins
I wouldn't put a large amount of any coins in an exchange. I look at exchanges like a public atm in a convenience store... okay for the occasional quick transaction, but not a good place to do your long term banking. As far as coinbase goes, I've used coinbase for a little over a year and they're very reputable. Any issues or questions I've had has been dealt with the same business day. I'd recommend them to anyone who needs an exchange to use. That being said, they have been know to block payments to known gambling sites on occasion, so you may not want to send/receive to/from coinbase if you're playing dice. If you're going to be dealing with any large amounts of BTC, consider a cold/paper wallet rather than an online exchange. After Gox, I think everyone involved learned the hard way.