On our last trip we decided to start with the rental. We normally do not buy alot of extra stuff when visiting WDW, but my DD10 wanted to try it. I was also concerned about lugging PM around the parks.
To my dismay it was alot of fun, and we ended up purchasing. Both my DD's 10 & 17 had a great time with PM, they loved all of the stories and information that he gives and when riding the buses they played games with him. He asks questions by using the right or left hand the kids would answer yes or no. He also tells jokes, and when we were in MK about 30 mins before a show in front of the castle he reminded us that there was going to be one even though we were no where near the castle.
For us he was worth it, we can bring him on future trips and there will be updates to the information gives.
There was also no problem carrying him around the parks, we just clipped him to our backpack where we could still feel him vibrate.
The only problem we had is which DD could press his hand when he had something to say.
Denise