I have a 3 LED mini-maglite conversion, I like it. Pretty bright for a small light. The batteries have lasted along time. The bezel can be removed, which activated the LED's, and it can be used like an LED candle.
Plus, lets not forget the biggest problem with AA maglites, is that bulbs last a very short time before hazing over/burning out. The LED's will last a very long time.
I have a 3 D cell Maglite, and a 6 cell Maglite, both have 3 watt LED replacement bulbs. The 3 cell is probalby about as bright, but bluish. It seems to be easier on the batteries than the original bulb.
The 6 cell is just a hair bright than the 3 cell with the LED. But according to the LED maker, the batteries should have a much longer useful life.
The LED seems to have enough juice to be a good utility or work light, maybe for the car if you have to make some roadside repairs, or a light in case the power goes out for a while. Or a good camping light.
The beam isn't that focused, so use as a "tactical LED Maglite" is probably a less then ideal application.