Simple Comic for Mac is a fast, lightweight comic reader for the Mac that will open a number of different file formats. This makes it very portable, and because it opens and reads comics so quickly, it's a useful tool for those with large libraries of CBR files.
Fast to install and open: Simple Comic for Mac downloads and opens in seconds. While it requires security verification on newer Macs because it is not in the App Store, it takes almost no time to get open, so if you have CBR files or other ZIPs or TAR files that need to be opened to read your comics, this will do it fast.
Intuitive interface: Once open, use the File menu at the top of the screen to open your existing comic book files. Simple Comic does not allow you to download comics, nor does it come with any files, so you'll need to have a legitimate source of files from another source; but once you do, this will open them fast and make it easy to read them on any size screen.
Fairly limited in scope: Simple Comic is open source and free, and it does everything you need to read comics, but if you want something more powerful for storing and cataloging your comic book files, this isn't it. It will open a comic archive, and can even capture or bookmark pages in it if you want to come back later, but this is not iTunes for Comics.
If you need a straightforward comic book reading app for your Mac, then Simple Comic is what you're looking for. It's fast and easy to download, offers streamlined interface settings for opening and reading your comics, and doesn't bog down your computer in the slightest -- a great all-around app.