While most independent studies show the Pro version of this software to be amongst the top five most effective antivirus programs you can run, the free version is a totally different matter.
The free version of the Avira Antiver software is not worth what you pay for it. After testing this software for an extended period of several months the software did not detect one single virus on the computer tested it on. While it is remotely possible that there were in fact no viruses reached the computer at all during that time it seems a really strange result given that the antivirus software that I tested immediately before that and immediately after that have both detected viruses. I suspect that the issue is not that there were no viruses during that time but rather that because the free version of the software doesn't scan emails that the software never detected them. As I generally find that I can identify viruses at least as accurately as any of the antivirus software that I have ever tried there is a near zero probability of my accidentally trying to open a file containing a virus - which would account for the software not having detected any viruses since it only runs a second line defence system of identifying viruses when you try to run them rather than a first line defence system of trying to identify viruses as they enter the computer.
In return for giving you the lesser half of an antivirus program the software displays a popup advertising the Pro version of the software every time it downloads updates (which happens at least once a day). The ads promise that if you upgrade to the Pro version that you will get both the primary part of an antivirus system (that scans emails) and anti spyware as well. Unfortunately there is no trial offer for the Pro version to allow you to actually see those components in action and so you are left to judge whether that upgrade is worthwhile based on the results that you get from the free version. From the results I got in running te free version I certainly wouldn't consider upgrading without being able to trial the Pro version first - especially since most of the other top five antivirus programs offer a trial of their full antivirus software.