OK, I'll be the first to venture a review of this new version of Carbon Copy Cloner. First off, this may not be an essential upgrade unless you want or need the new features in version 5. For instance, version 4 is listed on the Bombich web site as High Sierra Qualified. At the same time version 5 is described as being designed for APFS and High Sierra, macOS 10.13. Which means, I think, that it can handle the new file system in Sierra appropriately. So one reason I upgraded was to be on the safe side in that regard, though I won't be using High Sierra right away (as it's still in beta testing as of this post).
Among the new features I find useful is an improved file filtering window which, instead of just noting unchecked files, lines them out in red to make them easier to find in a long list, which can be helpful in custom backups. Just as helpful to me is the ability to group tasks into groups, which shortens my rather long task list. There are some additions that will help new users, including Guided Setup and Restore, which can walk you through the cloning and restoring process. There is also a Cloning Coach that can locate issues and offer advice.
Check out the new features page at https://bombich.com/features, which includes a side-by-side feature list so you can compare versions 4 and 5. I found this particularly helpful in making my decision to upgrade.
That said, I've been using CCC since the old days when you could run it for free indefinitely. I started paying for it when I began using it more regularly. The upgrade from version 4 is 50% off the regular price, which is a better deal than you get with many expensive apps.
If your backup needs are more basic, SuperDuper! is easier to use and costs 25% less. Though for $12 more you get a whole lot more power with Carbon Copy Cloner. Among other things, unlike SD, CCC can back up over a network. Then again, version 5 has a Simple Mode that makes basic backups easier to visualize and manage so you don't actually have to be a propeller-head to use it.