Love it! New version is coming out in one hour for people who pre-ordered.
Anyway, you can try before you buy, it's fully-featured but time limited (21 days I think?). That's what I did, and I'd decided to shell out the money in less than a week. Try it, see if it works for you, then decide.
It's essential to my brewing. Could I do the math and record keeping by hand? Certainly, but Beersmith makes it faster by orders of magnitude, and more convenient because everything is stored on the PC. The new version comes out in about an hour.