Comodo Firewall is actually pretty nice (apart lack of Vista compatibility), though resource consumption was rather high compared to some other firewalls. I'll give few reasons what i like and dislike...
1. I always want nice trey icons. Thats one and first rule for any of my programs. I watch those icons all the time in trey bar and i don't want some crappy jagged icons with awful graphics or meaningles icon like Outposts blue question mark. WTF!? If there is a traffic indicator, it has to be optional. I liked avast!-s spinning ball but i prefer it stationary, because i was staring at it most of the time, instead doing something productive. If there is an option to enable/disable it, thats cool
2. Must be P2P compatible out of the box (especially with eMule which puts every firewall to a test).
This means it should act as Stealthed but should also not drop important packets and choke itself on resource side like ZoneAlarm does with eMule (starts to consume massive amounts of memory and CPU, badly affecting PC's speed). Sygate, Outpost, Comodo and Windows Firewall never had such problems.
3. There has to be 2 modes, Basic and Advanced. Some prefer all the features and tightest leak control (Advanced).
I don't need that as it's annoying (for me alone) but i like to keep basic control over programs connecting to internet (Basic).
So, a program checking without crosslinking over DLL's and other mechanisms. Just direct programs connection monitoring. I don't want firewall to be annoying, which becomes quiet fast even if you have massive programs database.
4. Logical and easy to use interface with settings properly categorized and arranged so you don't have to look for them over entire interface.
5. Warning popup has to be nice looking, peferably displayed as popup above clock (similar to blue VPS update popup just a bit different so you can notice the difference and of course a bit larger) or similar to McAfee Firewall popup. I liked that very much. Also info on it is displayed nicely so almost anyone can understand it.
6. It has to pass ShieldsUp tests with flying colored numbers. I know it's not much but it's a basic thing that every firewall worth using should pass (while still allow P2P tools to work properly!, this part is especially tricky because most of firewalls pass the ShieldsUp but bork up the P2P apps to the max, mostly with it's ping handling engine!). Comodo required tweaking in the Network Monitor part to even work properly on both fronts (as mentioned earlier).
So much for now. I'm really looking forward to test this tool, hope there will be a free edition of it too