I guess it all depends on what $150 means to you. For me, it's enough money to think twice.
We did MemoryMaker once -- during a once-in-a-lifetime 3-generation family trip, and although it was nice, I didn't feel it was worth the cost at all. The on-ride photos were cool, but they're all grainy (and some didn't even come out) and not of the quality where you'd want to frame it and stick it on the mantle. The photos we had CMs take (meaning the whole family was in the photo), or that we took ourselves, were as good, or better, than the photos taken by the professional PhotoPass/MemoryMaker photographers. (I should also add that the "Magic Shots" weren't anything we were interested in, and we asked CMs not to even bother doing them -- if you want to see Disney characters photoshopped into your photos, it has that value.)
In short, if you hate the idea of carrying around your camera, to the tune of $150, then it would be worth it to you. If you have a halfway decent point-and-click or phone camera that you don't mind using (or asking any CM to use) to take your own photos, then you could take that same $150 and have a terrific meal at a table-service restaurant, or another night in a value hotel, or a couple more days' worth of park tickets, or buy a couple of big custom hardbound photobooks on Shutterfly or Snapfish when you get home to commemorate your trip.