Got one on my G26. It's accurate enough to consistently plink cans at 50-60 feet. Indexing your finger on the side of the gun, a push of the new takedown lever turns it on. I've found that most holsters turn it off automatically when you reholster, which is a plus in my book - no chance of wasted batteries.
The first time you install it, you swap the takedown lever and the spring under it for lasermax parts. The new takedown lever is slightly larger, which is actually pretty nice when you go to field strip it. The old guide rod still works so you can swap in the cheap one at the range to save wear and tear on the expensive one.
I've only found the individual batteries locally - and incredibly overpriced - at Radio Shack, but they're readily available online, and fairly inexpensive. Still, I'm on my first set after about 5 months, and that's with plenty of "showing off" of my new toy.
I did notice on two occasions, both after extended use, that the laser faded to quite dim. I thought I'd killed the batteries, but an hour later and it was fine again. I don't know if it was overheating or what, but it was kinda weird.
I chose it over the Laserlyte because I have tritium night sights that I didn't want to give up - and it's plain ugly!
I chose it over the Crimson Trace Lasergrip because my trigger finger blocked the beam when I had it indexed alongside the frame.
Since the G26 doesn't have a picatinny rail, the only other option seemed to be a trigger guard model, and, I didn't want to replace my holsters.