I guess if you want to actually consider this a Ghibli score it's an incredible piece of work. Ponyo was good but it was too simplistic in nature and I'm sure that was the directorial intent of it given the average age of the intended viewer and the age of the protagonists and such. Howl's Moving Castle was okay but I generally don't like that much brass in my orchestrations and it was definitely a huge variation from Joe's normal orchestrations. Top 4 Ghibli scores, in order, are Spirited Away, Princess Mononoke, Laputa and Nausicaa. If I had to rank this new one I'd probably put it at 5.
Though if you want to compare it to Joe's recent works, non-Ghibli included, I think it falls a little short of what he's capable of, and that could be either due to direction or the medium or the game. Some of the movie and tv shows he has composed for recently (Watashi wa kai ni naratai [I want to be a shellfish], Sake no Ue no Kumo [A Cloud on the Slope], Okuribito [Departures], Akunin [Villain]) have been far and above some of his best work of the decade and I would put it somewhere on the level of Sonatine and HANA-BI scores.