As long as i'm using Bittrex for trading, there have never experienced any obtacles, withdraw and deposit continue smoothly. So Bittrex is indeed a recomendation for those who want trade altcoin especially there are lots of ico coins that enter
Pros
Bittrex has never experienced a violation or lost customer funds
Cons
High trading fees 0.25% per transaction and does not accept fiat currencies (USD, EUR, JPY, etc.)