I generally like LEDs except for:
#1. Brightness. Most LED flashers are too bright so I rarely use them. And oftentimes people put way too powerful bulbs in the GI. Hard to play a game when you can't see the ball. Inserts usually benefit from the brightness though.
#2. Strobing, ghosting etc... This can usually be rectified but I absolutely hate when it is not. I won't play a game that strobes.
#3. Poor taste in color choice. Skittles.