I used Comodo Internet Security for about a year. It protects you very well but at the price of receiving annoying alerts about the normal actions of every program on your computer. It causes problems getting full screen applications like games to work right. You have to put Comodo into training mode where it allows everything the first time you play the game so the appropriate rules are made to allow the actions of the application. Since they have added the sandbox, the problems with getting games and some other things to work have gotten worse. It automatically sandboxes anything that is "unknown", meaning anything not in Comodo's whitelists of safe things. The whitelist is pitifully small and does not include any game software since Comodo has stated that they will not whitelist games. Not even the hugely popular World of Warcraft and all the Steam offerings. These problems have led me to only use the basic Firewall part of Comodo coupled with Avast! 5 Free.
If you want total protection from everything and can put up with alerts for every action of everything you install that isn't flagged as safe by Comodo, then maybe CIS is for you. The problem for me is that it "protects" you even from things that are known to be safe by most of the civilized world and makes you jump through hoops to make a lot of things work. As far as the company goes, Comodo is well intentioned and honorable. For me , however, all of their offerings are too aggressive and not user friendly at all. Some people, mostly those who want to see every action that everything does and who like tinkering with everything on their system, like Comodo products but they are not for me. The basic Firewall though, without the HIPS and sandbox, works very well as a two way firewall and I would recommend it over things like Zone Alarm and Online Armor or Outpost ( with the HIPS turned off in them too of course)
I have not tried the full AIS suite so I can't comment on it. I have gathered from reading though that the firewall is good and silent and that the sandbox feature is not automatic but on demand. These things lead me to believe that most people would prefer it over Comodo.