Well the batteries will only die sooner if you use the remote more, and that has nothing to do with the software (other than it actually enabling you to use the remote more).
I'm currently trialling it and I think it's a great little app, however, it does have some annoying little bugs. Sometimes it just won't use the virtual keys and virtual mouse actions at all and it takes some fiddling trying to get it to use them again.
Overall it's a great little app and not priced badly either (you currently get 5 off if you buy before the final version is released bringing it to just under 10 if I'm not mistaken).