The wavelengths are spiky compared to incandescent, and the LEDs flicker if they are not DC-driven.

The flicker is pretty annoying because the transition is an abrupt on-off. Where I am the city had the bright idea to wrap LED ribbons around the poles in the downtown area to make it look more interesting. They connected the ribbons without diffusers directly to the power source of the streetlight. So what has happened now is that as you drive or walk you are looking directly at an unshielded flickering LED.

I still continue to install incandescent bulbs. They look better, and as I live in a cold-weather country the heat they generate is welcomed.