Market makers customarily offer you their own prices, based totally on the price that they expect to get on the ECN. When you open a deal they have to match it in the ECN to cover their risk. Clearly here there is room for the price to modify in the moment between you clicking the button and the deal going on to the ECN. This is slippage. For that reason scalpers and market makers are not a good mix and could be unwelcome.
On the positive side, market makers could be a good choice for a beginner. They will often provide good technical analysis, stories alerts, a user friendly platform and a demo account. This is a really vital factor for many new traders choosing forex brokers.