I use it in my classes. Most everybody loves it.
Here are the precautions.
The directions are horrible. HORRIBLE.
You need to remove the batteries COMPLETELY when not in use. Mine uses a brass case that drains the batteries if I don't completely unload them. The batteries are hard to find and expensive locally. You can find them on ebay for pennies however.
Until you figure out how to assemble it and disassemble it, do so in a closet or corner in case any tiny parts spring out or fall away. Once you get a feel for it after a few days, you will probably not have to be so cautious.
After putting in the batteries, I find sometimes it takes 10 or 20 seconds to "warm up"
Despite all these precautions, it works very well and is worth it for working on your aim and trigger squeeze during dry fire. If you see a line instead of a dot, you know the muzzle is moving and you need to work on your trigger pull. It's easy to see bulls-eyes, you can use the reflective target they send you or any shiny material. It gives my students immediate feedback and I get positive reactions to it. Just don't let it aggravate you the first time you try to assemble it and get it working. I can now get it put together and broken down in seconds. Just like many things. it takes a little trial and error