Are you dining at character meals that have photos that aren't otherwise included? (Akershus and Cinderella's Royal Table have prints that are included so don't count them for this)
Are you willing to stop and have lots of PP pictures taken?
Will you be riding lots of rides that have photos on them?
bonus: are you doing Pirate's League?
If you're doing most or even all of those, + is great.
If you're ONLY interested in the ride photos, wait until you get there and buy Attractions +, which is way cheaper. It gives you ONLY the digital images of the ride photos.