It depends.
You don't have to rent the battery. You just pay more in the 1st place.
Its not hidden either - the salesman was very up front about it, explaining the various ways to run a Leaf.
I very much doubt I'll go down this route, but it might just work for me. I do a lot of miles around South London and the TD4 auto is not very economical - 20-30mpg typical depending on the length of journey. Today I did about 15 miles with 2 stops and I have another of about 10 miles with 1 stop to do in a moment. The Leaf would be perfect.
I have a friend who covers about 25,000 miles a year in one and it has slashed his fuel bill big time, and it only costs pennies to charge up. He has driven it down to Devon and back. You just have to stop every 80 or so miles and do a rapid recharge, which takes about 20 minutes or so and charges up to 80%. He said it took a little longer, but as he has a small child, he needs to make frequent stops anyway. And with the Nissan charge card which came with the car, it didn't cost him anything to charge the car up.
He does have a huge choice of vehicles from a GT-R, several Yeti, a tank, and a few other Skodas.

so spoilt for choice.