I am going to repost my opinion on trading here. I originally put this in the firehose thread:

IMO the smart money trades off exchange, preferably using the bitcoin-otc web of trust. Using this forum's trust database is a distant second, considering how many people stay logged in all the time, and how many times bitcointalk itself has been hacked.

The exchanges are better suited for weekend warriors that fancy themselves day traders or small retail purchases.

Mt Gox is only the latest in a long line of cryptoexchanges that have lost significant amount of user funds.

Until the crypto economy is bigger, we probably won't see an exchange that does security and oversight correctly because the space just isn't big enough to afford a reliable service. The exchanges just can't come up with the capital needed to do it properly.

Instead we still have a bunch of pikers that take advantage of the low barrier to entry. They open an exchange and only realize they are in over their heads after their users' funds are stolen.

But who knows, when the floating point decentralized asset exchanges start cropping up, maybe centralized exchanges will be rendered obsolete. Decentralized exchange may be here before a well-funded and well-run centralized exchange emerges.