It depends on how much you ski and spend there. I have been a Club Vertical member for quite a few years, though I do not ski Northstar exclusively. With the points accumulated from ski days and spending money in the Village or on hill, we get food coupons, parking passes etc. We have even turned them in on private lessons. Northstar has some very good L3 instructors (even a member of the National Demo Team).
Northstar has better on-hill food than most mountains so it is worth spending money to eat there. We'll always bring our food to Alpine but don't mind eating form the establishments at Northstar. Money spent goes back for points used to get food coupons next year.
Also after the first year you are in, you have the option of trading back points for $50 off on membership next year. The other benefit is that often the line in the Club Vertical line is much less. Extra ski time - priceless.