Pros:
Allows you to chronograph every shot, without causing any issues with barrel harmonics.
Very easy to deploy & run multiple rifles over it.
Within ~1-3 FPS of my Magneto Speed every time I've measured against it.
Allows you to extrapolate BC of bullets, because it tracks most out 50-100 yards.
Cons:
Interface is clunky, non-intuitive, and slow to respond.
Internal AA battery life is horrible; everyone is using USB battery packs with them.
Will require some ramp time to use... nobody is powering a LR on out of the box and using it seamlessly without an instruction manual.
Can trigger off other rifles at crowded ranges.
Will require some experience before you can get it to "work like it should" all the time.
Aiming the unit can be a PITA in some circumstances.
You gotta take care of them; I've read reports of them being fragile, and I had to send mine back because it got knocked out of calibration.
For a lot of people it's the best chronograph on the market (myself included), but it's going to take some time & effort on your end to learn how to use it, and how to deploy it correctly.
Once you get that down, they're freaking amazing.
Edit: You'll also want these accessories.
A carrying case of some kind, either from LR themselves or a Pelican etc.
A base plate, either from Lab Radar or someone like Arko machining.
An external USB battery (this is a requirement, these things don't run for very long off internal batteries).
Recoil/Inertia trigger - Triggers off recoil of the rifle vs. sound...invaluable if you're shooting on public ranges.