I voted that I liked the change because I don't think critical hits should be routine for anyone, even higher level characters.
As a DM, I don't think characters built around 3.0 Improved Critical / keen are too powerful; indeed their power waxes and wanes a bit too much for me. Against most opponents, if the dice are kind to them, they are fine; if they run up against enemies immune to crits (undead, constructs) they are much less effective. So PC's using this combo are always weaker in the long run (because they use lower damage weapons), while NPC opponents using it are almost always stronger against the PC's. (Unless your PC's happen to be undead or constructs)
Additionally, I think players who have a blast critting half the time are the same people who dislike it when a monster does so to them.
The option of 3.0 IC/keen is deceptive. Players think they've found a clever way to do more damage, but the fact is that taking it can screw them more often than not. And the DM is often blamed for this, every time an undead or construct shows up.
The only part I dislike is that logically keen and IC should stack. A person who is exceptionally skilled with a longsword (Improved critical) should get some benefit when picking up a keen longsword. I just don't think the threat range should be doubled multiple times. Crits that are too common skew the game against the PCs. I'd rather see it doubled the first time one of these effects is taken, then incremented by one for each additional effect. So I would have voted for a "mixed feelings" option if one were available.
It's easier to throw up a messageboard post than to write a core rule that needs to be clear, however, so I know I don't have all the answers.