I'll second that Improved Critical is not a feat that should be taken. Having to not worry about activating Keen is all well and good, but by the time you get the feat, the list of things worth adding to your sword is... painfully small. I took it with a Bladebound character, and he was constantly scratching at the +5 cap for weapons. I wouldn't say it's a trap option, since it certainly does help your character, but I certainly felt limited.