2004 WGP Karnivor with stock pneumatics and Planet Eclipse E2 Eblade upgrade.
1999 Right Feed WGP 'cocker with Bomb 4-way, Planet Hinge, Palmer's Ram/LPR, AKA Sidewinder, AKA Tornado Valve, AKA Lightining Bolt
Not substantially better than water or squeegee
I've been using Plexus for years, as it has been in my and my buddies' kit bags at most of our outings.
Even Spray: The can puts an even spray of the liquid on your goggles, and it's easy to avoid spraying all over your entire mask or kit.
Needs Microcloth: Like every other solution out there, you need a microcloth or other fine, non-abrasive cloth to clean the lens. Otherwise, the solution will streak and leave itself and paintball oil behind.
vs. Water or Squeegee: In my experience, and through testing, I have not found Plexus to be much better than water or a squeegee; the result is the same. I have noticed that there is less of the filmy residue of paintball oil left after using Plexus, but it's not a huge difference, and is barely noticeable when you get going on the field. A good squeegee generally takes both the paint AND the residue off, as does a microcloth.
A good squeegee and a small spray bottle of water is your best, most economical lens cleaner. I can't justify the money on Plexus when I have to use a squeegee with it anyway. It's not a bad product, it just doesn't justify it's cost.