I've been using my APL for a while now, here's what I've found...
-Cost. The light can be had for around $100
-The activation paddles are very easy to activate and ambidextrous
-Uses relatively common CR123 battery
-Comes with two mounting brackets---universal and 1913
-200 C4 LED output. It's a nice white light with a good peripheral cone.
-O ring sealed
-Lightweight. Weighs 2.8oz.
-It's not as bright as some lights on the market but brightness isn't an end all, be all on a weapon light.
-1.5hr runtime (but only uses 1 battery vs. 2 for most weapon lights.
Here's a review of the light with a side by side comparison with some other weapon lights at night, some shooting, and a discussion of the pros and cons: