Is bittrex safe with all securities?
At the present time now, I would say yes it is safe now. But I just don't know how long it will be safe, like what I said it safer than the other exchange platform. So, you can keep your coins in bittrex for the mean time.
Bittrex is safe in terms of trading and exchange. It is mostly used exchange for trading as it has high market cap and a good collection of coins.
I really don't know if it is safe for storing coins in its wallet because i have heard from many that never store your coins on an exchange. Although bittrex is safe we never know what might happen tomorrow. So if you are planning on to store your coins then an offline wallet will be a great choice and if you want to trade coins then bittrex would be the best choice.