Only last month, Elabdellaoui appeared set to cut short the loan as he struggled to settle.
But now Koeman enthuses: "I must say he is doing pretty well."
Feyenoord chief Martin van Geel admits they could still lose the youngster in January: "That's the deal with City. A decision has yet been taken, but the fact is that Omar gets little playing time. Soon we will see what for all parties is the best decision."