Ifill, who was signed for £800,000 this summer from Millwall has scored three goals in eight games for the Blades since his move.
"Paul has done very well," Warnock told www.sufc.co.uk.
"People don't know what he's going to do next - his unpredictability has created chances for us.
"I'm pleased he is running at defenders and there is certainly more to come from him. Defenders are paying a lot of attention to him in the way they did to Michael Brown and Michael Tonge a couple of seasons ago."