I hate it.
I use my phone as a GPS attached to the handlebar on my motorcycle. When in direct sunlight, the map colors suddenly wash out, and I have an almost totally white screen. I can't see the different contrasts of the different roads and trails and my maps become useless. It is suddenly all nearly white. Horrible. The other drawback is that even when plugged into a charger, the display suddenly is pulling more power then my chargers can output. So my phone battery slowly dies, even on charge, when in bright sunlight.
The only way to disable this screen oddness is to turn off auto brightness. But I like auto brightness. I'm playing with a replacement screen brightener now. It needs a setting to disable that oddity.