With its options for heuristic scans and security settings that are certainly thorough, Avira Free Mac Security for Mac protects your Mac in real-time against threats. On the whole, this is a competent free program that does what it's meant to do but with a rather slow performance.
Installation of the program on OS X Mountain Lion was quite cumbersome. We were compelled to force quit installer a few times before we finally managed to have Avira Free Mac Security for Mac installed correctly. After installation, the application still needed to download almost 30 additional minutes worth of updates. Once we ran a scan, however, the program seemed efficient enough. It managed to find one malicious program that a few other antivirus software applications did not. It did slow down our computer significantly while it was scanning, though, so it may be best to use it while running few or no other applications. The basic user interface doesn't have many options available, but everything necessary to run a scan is there, including quick scan and deep scan options, as well as a scheduler for future scans. The preferences are accessible from the standard Mac status bar at the top of the screen and allow for controlling how malicious objects should be treated, which is a nice feature.
Avira Free Mac Security for Mac doesn't come with a price tag, which makes it a very good product for almost anyone. Even though it's rather slow it will do a good job at protecting your computer.