That's the only alt exchange I've used that hasn't died or screwed its customers. There are a few other IFC exchanges but I couldn't imagine anywhere else would have more volume.
Bter for example has an ltc/ifc market. Apart from the fact Bter owes thousands of coins to customers, its trades over a 48 hour period only amount to less than 2 btc.
I've not heard of the majority of exchanges on here
http://www.infinitecoin.com/ifc-exchanges.html and a few seem dead anyway. With Poloniex you know they're going to maintain their markets and wallets.