I've a number of cordless drills, the only one I have w/ lithium batteries is a DeWalt 36v. I think the lithiums are an improvement for sure. The two batteries that came w/ the drill are somewhere in the neighborhood of their 150th charge, as far as I can tell they run just like they did when I got them.
They also don't have a "memory" like some older cordless drill batteries did, it's not necessary to run them all the way down before you recharge 'em.
Like mirage said, let us know how it works for you... Real world product reviews are something I'd like to see more of here in the tools forum.