In reply to a recent post of mine, madmacs0 responded with an assessment of Norton ... and a more balanced and informative post would be hard to find. Do read it.
I need to preface my remarks to explain why I have not spoken up on this subject here before.
I was an early adopter of Norton Anti-Virus when Peter Norton owned it. It, along with the even better Norton Utilities saved my bacon more than once when running Apple's Classic OS. At the time I would have recommended it to most any Mac user. Then Symantec bought Peter out and things went rapidly down hill. The last chance I gave them to get it back on track was SystemWorks 2.0 and Internet Security 1.0 back in the OS 9 era. Despite a number of bug fix releases, I had to disable most of it and then remove it entirely. That's the last time I actually ran a Norton product on any of my Macs.
So I have no current experience with either NAV or the new iAntiVirus at this point and can't speak with authority on their worth. So feel free to ignore anything else I may have to say here.
I guess my bottom line would be that I think it has an undeserved bad reputation based on user experience from many years ago. I don't remember the last time I read a first person account of individual user issues in modern times. You chose your words carefully, which is appropriate, but I'll bet there are a lot of "experts" here who condemn it without ever having recent hands on experience.
There are a lot of reasons for their reputation, most well deserved. It's been said that Symantec never invented a single piece of software (not sure that's true any more, either), but rather purchased the works of others to either kill the competition or enhance their bottom line. They were a very different company in those days, with a different management style, etc.
So I wouldn't be surprised if it turned out to be at least as good as whatever has the best reputation among Commercial Mac A-V vendors today. They seem to be on top of most all the OS X malware, even though they don't spend a lot of time blogging about it. I know a lot of IT professionals who swear by their enterprise level software. I suspect that their software no longer behaves any worse than the others that operate at the kernel extension level (always dangerous for third parties). But their reputation seems to be their unending albatross.
I hope madmacs0 will not mind me copying his post like this.
Norton Antivirus (made by Symantec) has a very long and illustrious reputation for mangling Mac OS X systems, sometimes to the point where a complete reinstall is necessary. Among other things, it installs kernel extensions which are known to cause kernel panics and system freezes; it contains known and documented bugs which can silently corrupt Adobe Photoshop and Adobe InDesign files, destroy a user's ability to authenticate as an administrator, and (on PPC systems) can cause Classic to stop functioning; and Symantec has on at least two occasions now released flawed .dat file updates which erroneously report certain critical Mac OS X files as "viruses." (Deleting these "viruses" causes damage to the system that in some cases renders it unbootable.)
Norton Removal Tool (Symantec Uninstaller):
And now this, from 11 January 2012:
Lawsuit Claims Symantec "Scareware" Warns Of Fake Threats To Sell Upgrades
No viruses that can attack OS X have so far been detected 'in the wild', i.e. in anything other than laboratory conditions.
You will find this User Tip on Viruses, Trojan Detection and Removal, as well as general Internet Security and Privacy, useful:
The User Tip (which you are welcome to print out and retain for future reference) seeks to offer guidance on the main security threats and how to avoid them.