I don't trust them and this recent change to the ToS should ring alarm bells...

http://ethereumworldnews.com/poloniex-changes-rules/

The biggest change of all was made to Poloniex’s Arbitration section of the ToS. There have been quite a few rumors circulating regarding the potential insolvency of the Poloniex exchange. According to the new terms, all users trading on the platform waive their right to participate in a class action lawsuit or class-wide arbitration. This addition is not uncommon for cryptocurrency exchanges, yet it will likely only fuel the rumors.

Hopefully they come back up and don't scam people, I took my money out weeks ago, but I don't want to be proven right in this case, the fallout would be huge.