I use critical hits and misses because it adds to the enjoyment and unpredictability of the game. But I have very simple rules which do not slow the game down at all.
If a natural 20 is rolled I have the player roll again; 1-5 is no extra damage, 6-15 is double damage, 16-19 is triple damage, and another 20 is quadruple damage. Very simple.
If a natural 1 is rolled I have a percentage chart copied from a Dragon mag. that has anything possible from nothing happens to dropped weapon to broken weapon to strike party member to strike self. I keep it clipped to my DM's screen - no searching for a chart. And if weapon break is indicated its gets a save vs. crushing blow. Very simple, no math involved. Plus it helps to eliminate weapons from the game making room for new weapons. And you can't accidentally kill yourself or chop an arm off.
"Plan?...There ain't no plan!" - Pigkiller