I think it is roo looking, but it is a little early to be 100% sure. I'd feel maybe 85% to 90% confident.
That is a pretty bird but the speckling from the Sussex is a recessive gene. It will express itself in the juvenile plumage but expect it to disappear in the adult plumage. Now if you cross that chick with another bird that has the speckling gene (called Mille Fleur in Henk's calculator) you could get some real pretty adults.