Smooth and secure!
It can be tricky. The buy/sell section is practically the same as the trade one, but with different interface and higher fees. As for the rest - no claims yet. I really like their trading platform - it is easy and processes orders relatively fast.
One of the main reason why I trade on Payzet and contribute to it, is the outstanding privacy, security and censorship resistance. Small drawback: you do need a small amount of BTC upfront for security deposit and trading fees.
Quick deposit and withdraw but bad and slow support.