Have used this couple of times now for crypto-crypto trading. Everything has gone well and It's fast&has low fees
I wouldn't recommend using fiat at the moment, it has insanely high fees. For example I checked earlier today when 1 litecoin was $50 that how much would it cost to buy one through them. Well the price was something like $80 for 1LTC which is very high price. So you pay $30 for extra fees.