I'm an LED flashlight fiend and have been for a while now. It's amazing how much lighting power can fit into a small package these days and it seems to increase all the time.
A couple of war stories:
1. My first fairly potent one was from the now-defunct Gander Mountain. It was pretty tiny and rated for 220 lumens. It was awesome except for one thing: after a few minutes of continual use, it would get so hot it was almost unbearable to hold.
2. A few years ago, I bought one from Amazon with a very high (and likely bogus) lumens rating. If you push the cylinder forward to focus the beam, the light pattern would become... square. Not kidding.
There are some annoyances with LED flashlights that I've encountered at times. One is bogus lumens ratings. I've seen where a higher-rated light was much less powerful than a lower-rated one. It's almost to the point where the ratings mean nothing because so many of them are inflated.
Another is the switch function on some. I like for the switch on my flashlight to perform exactly two functions:
1. Turn the light on.
2. Turn the light off.
When I press the button to turn it off, I want it to go off, not switch to lower power mode, then flash, then turn red, then green, then blue, then infrared, then whistle Dixie. They seem to have gotten better about it these days, where they don't force you to walk through all of this.