Never keep money on exchange - this is first gold rule in crypto. Always try to avoid this at all cost, no matter how long exchange is in business and how trusted they are. if I keep my money on my favourite exchanges: Mintpal and BTC-e today I will have nothing left. I didn't expect Bittrex to disable user accounts without any statement, it will impact their business badly.
btc-e actually restarted as wex.nz and they are trying to refund their customers. Yes better in a wallet where you control private keys but if you are trading you dont have much of a choice