This is one of the best Mac utilities in recent years. I found a review that covers it in detail. There's a reason SD gets nearly 5 out of 5 stars:

I've used SD for nearly a year and find it wonderful. It's a great Mac utility; elegant, with many features, not one of which gets in the way of what you want. The learning curve is perfect. Simple for basics, step-by-step to more features.

Here's a review I found that says the same thing:

http://www.mac360.com/index.php/mac360/more/my_favorite_mac_backup_utility