Since summer '13 I've racked up 4 million steps and over 200 rare candies so... Yeah I use mine a bit.
And @ warsmith, yes, you will lose all your watts, steps, and routes when you start a new game. If there's a route you don't want to lose access to, you can keep a pokemon in the walker, start a new game without retrieving the pokemon, and then use only the "receive gift" function instead of "return from stroll".
I already have a Xatu that I've permanently assigned to Sinnoh Field for gathering rare candies :]