Yes it is still good. I suggest you read about how to hand raise rejected joeys HERE
. There is some fantastic info there that really helped me with my Duncan (now 12 weeks oop) when he was rejected at 1 week oop.
I used Esbilac puppy milk replacer (found at most petstores and walmart) and a needleless syringe to feed Duncan. The formula needs to be warm, not hot and also the joey must be warm or it won't eat. Make sure you stimulate him to go potty after feeding as they can't do that by themselves at that age. (you can read about that on the site too)
If you have any questions or are having any problems, feel free to call me 913 544 8090. I'll help any way I can.