Well, it depends mainly on the account types you choose. They have two account types and the main difference is the execution style, and consequently the spreads. The first one, the Classic account type, comes with live execution, with spreads starting from 1.7 pips, and no commissions are charged by the broker.
The second one comes with ECN execution, and understandably it offers tighter spreads, sometimes even ZERO. As usual, with an ECN account type, you will need to pay a commission of $4.5 per lot per round.
So do your maths carefully, and see which one suits you better.