This particular product has had a very bad history of not being "philosophically" sound. For instance there was an issue with it not protecting your computer when you'd lock the workstation, or when a screen saver went on, etc. etc.
I understand it's got pretty buttons and everything is cute but if the product doesn't do what it was created to do then what good is it.
If you search these forums you'll also find out that ZoneLabs as a business isn't exactly the quickest to fix something that is wrong or even admit they have aproblem. IMHO that's not the way to run a "security" based company.
Anyway, it is my opinion, but I've tested most of the major firewalls head-to-head and there weren't many that I couldn't crash (or worse) even when they are configured properly.
It's ultimately your decision but that's just not my first choice, or even my 10th choice for that matter.
Good luck.
