It beats every place in Iwate, Miaygi and Yamagata that I've been including Appi.
I've been going to Onikobe all through 2005/2006 and this weekend was reinforced by an awesome weekend. Stayed at one of the pensions as part of the resort and was first up the mountain both days. The park seems under used but there are some jumps to do, a box and rails. Some nice wide runs for carving and beginners and lots of terrain to find. The best thing about this place I think is that it actually caters for high intermediate level skiers/boarders in a way no other ski place in Miyagi or Yamagata does.
Shame they don't open the top of the mounatin very often (they say due to wind). In the right conditions there is acres of powder and some back country routes to hit.
Food is good and staff friendly and relaxed. Child care is only 1000yen per kid per half day - cheapest we've found (a third the price of eboshi zao).