iZip Unarchiver for Mac impresses with its comprehensive archival type support and reliability. It's ideal for all those odd archives that can't be handled by the OS X's Archive Utility. However, because of its limited features, you cannot use it as an all-in-one archive solution.
iZip Unarchiver for Mac utterly lacks configuration options. For an app of its kind, though, this isn't a fault. The app's main window is a bulletin for premium products made by the same company and doesn't offer anything worthwhile. We recommend that you use the app as you would the native Archive Utility, by bringing up the "Open With" menu on an archive. In terms of speed, iZip Unarchiver proves to be slower than Archive Utility; while unzipping a 150MB archive, the app took roughly 12 seconds, while the latter took only a little over eight.
If you work with a lot of archives on a daily basis, you'll find iZip Unarchiver for Mac useful and worth installing. However, if you don't deal with unsupported archives too often, you'll be better off sticking to Apple's Archive Utility, which is faster and better designed all around. That's not to say you shouldn't give this one a try.