I agree. My mom also debated whether or not she should get one because she thought maybe she could walk it. A day at Epcot and a day at Animal Kingdom was all it took to convince her she did the right thing by renting one. She saw so much more than she ever could have if she had tried to walk it. And she enjoyed it a 100 times more since she didn't have to hobble around on her sore ankle for 7 days and wasn't completely wiped out at the end of each day.
Also, SkyGirl makes a good point about park hopping. If you rent the Disney
ECV's,
you have to pay at each park. If you go to two parks in a day, that's $90. (It's $45 per day now with a $20 deposit.) And you take the chance that the second park might not (and likely won't) have one available. If you rent your own, you can park hop to your heart's delight! We typically stay offsite and park hop, so it was nothing to throw the ECV in the rental car and drive off to the next park. Disassembles and reassembles in less than 5 minutes. If you're staying on site and using Disney transportation, you may not be park hopping as much, but it can still be done with an offsite ECV you keep with you. Might just take you a little longer to get from place to place. As for getting on and off the bus with an ECV, the three-wheeled ECV's have a lever that disengages the gearing and allows you to push the ECV. You can always have someone push you on and off if you're nervous about driving it on and off the busses and Monorails. But my mom had never driven one before and she did just fine pulling onto and backing out of the Monorail.