Now, I have to say that I think the calorie counter is a rough guess at best. It only asks for my weight to compute the calories burned, and didn't ask for age, sex, height, etc.
Additionally, it obviously doesn't track if I'm going up hills (I've got a few killer hills on my walks) or on level ground, and I'd imagine that carrying around a 25 pound of mulch would burn additional calories as well.
But, overall it's a fun new toy.
One thing I've learned from it. You don't burn any calories sitting in front of the computer, so I'm off.