As with most things, depends.
It depends on how long you're there for, if you meet characters frequently, if you do meals that have photos, and if you're willing to stop at most photopass people you see, IMO at least.
We thought it was worth it, even good value, for a longer stay. We bought it in advance so it was $150, but broken down it was between $10-15 a day for us. That amount was totally okay with us to get good quality pictures each day of our trip.