I've done trips with and without (never the Plus, though, as we don't do too many character meals anymore, and aren't really interested in ride pictures). I managed a small share twice - just for some of the students going on the same high school trip as my kids -- and that worked out well, because even if the kids didn't use it much (and some not at all), the parents didn't pay more than $10 for pictures of all the performances the kids were in.
I wouldn't do Photopass again by myself (one caveat - once we're toting grandkids around -which better still be a few years out - I may change my mind). BUT! If you have someone in your family who expects to audition for American Idol, you may want to consider it - they take a lot of pictures that you won't be able to take, and that was worth it for me.
The photographers can't always be found, sometimes there's a big line, they aren't always the greatest pix. Sure, the magic shots are cute, but nothing you can't live without. And for the PP who said they didn't have the nerve to ask the photogs to use their personal camera, don't worry about it! They're happy to do it. They won't take more than one or two with your camera, but that's enough. And lots of CMs around the park will be happy to do that as well - don't limit yourself to a Photopass person.
If you do purchase Photopass, don't walk past a photographer without stopping so you get your money's worth. Have pictures taken of not just your large group - individuals, couples, etc. If it's not busy, they'll do as many as you want. And ask every one about magic shots - some do them, some don't, and you don't always know which will. We watched the Dapper Dans a year ago, and there was a photog just snapping pix - she noticed the Photopass card on my lanyard, and put a bunch of pix she had taken on it (unfortunately they were all of just me, not me and my son, or of us with the Dans in the background, so they weren't that interesting). Keep an eye out for that kind of opportunity, and don't hesitate to ask for something you'd specifically like.
And if you are having them take your picture - do something fun. That trip a year ago was just me and DS21. Some of my fave pictures are when we did something silly - I leaned up to kiss his cheek when one pic was taken; we knew there was going to be a Tink magic shot and neither of us care for Tink, so we screamed for the picture, etc. Don't just POSE.