IMO, anything under 10 pages is perfectly fine.
I'll look at someone's wishlist and have an idea in my mind which titles I'm planning on getting. If I'm in a situation where I'm going to flip through all pages of someone's wishlist on a whim, 10 pages would be about my limit I would bother to look through.
Of course, if I'm looking at someone's wishlist on a whim, I probably have an idea of what platform I'm considering, so I'll just look at their wishlist for a specific platform.