Used Comodo off and on since they began offering their firewall, and was never infected or had a problem. That ended with v6914 which was a disaster, followed by other disasters. I removed it from my computer and said I'd never use it again, which with me means I might if they get the thing fixed.
I will argue with anyone about Comodo's high CPU or memory usage. Firewall on my laptop used no CPU and only 20 - 25 MB RAM, light and no noticeable slowdowns. I haven't used the antivirus because with the firewall properly configured you don't need it.
Nothing is invincible, and I'm sure there are things that can beat Comodo FW no matter how tight you configure it, but Comodo is arguably perhaps the strongest firewall on the market when properly configured, and it's free. And, I feel myself wanting to give it another chance. lol
Their antivirus is a different story in the various tests. In the real world, the couple or three people I'm aware of who use Comodo AV say it works fine and has protected them, and they swear by it. I can only take their word that it works. I've never used it, and 2 or 3 people isn't enough to make a statement.