There have been a lot of reported problems with FL including hardening to the point that it prevents the firing pin from igniting the round in the chamber. That is what I call a show stopper.
I had a discussion online about that point in particular. From my experience it is extremely important that you follow FrogLube's instructions exactly. This usually involves heating the part/pistol, applying the lube, letting it cure, and then
wiping off the excess. That last part is extremely important and to me makes FrogLube rather unusual. Breakfree CLP, Ballistol, Slip 2000, the list goes on. These lubes are free flowing enough (not viscous) that excess oil is generally not a problem and will be thrown from the part or continue to flow (within reason, obviously sitting in a tub of said lubricant will prove problematic). FrogLube, on the other hand, can congeal if left in more than a thin film. This is especially true in the cold.
For me this manifested in the following way. On hammer fired guns I put a drop of lubricant on my finger and run it over the part of the slide (inside, center) that runs over and cocks the hammer. I performed this action on an HK P2000 many times. Months later I took it to the range and couldn't get a cartridge to fire for the life of me, including Speer Gold Dots. On taking it home I found the lube had leaked a little bit each time down the firing block and into the firing pin channel. It formed a gel in the cold that retarded the motion of the firing pin to the point where the cartridge wouldn't ignite. I had to use an aerosol degreaser to remove the build up.
Now in the argument I had online the other gentleman argued that because I wasn't careful to wipe the excess that the problem was a result of my own misuse. I will accept some responsibility there. My counter argument is similar to the above, in that I have never used another lubricant that could have such detrimental effects if left sitting. The other lubricants I mentioned above simply won't solidify to the same extent. The way I see it, FrogLube is a lubricant that must be applied with notably more care than its competition with little advantage over the competition, and potentially notable detriment compared to the competition if notable care isn't given. If you clean your firearms with even mild regularity, the long-lasting claims of not needing to clean your firearms so often became essentially moot. The whole point of this more expensive than average gun product is that you don't need to apply it as often, but most people still apply it as often anyway out of habit.
To paraphrase InRange TV from their piece on FireClean, it's modern day snake oil. There are specifically chosen anecdotal pieces of evidence that say it will make your life easier. Or you could just clean your guns. I have an AR that went a year and 1200 rds between cleaning on Breakfree CLP (by the end of which there was no CLP still on the rifle) and it was still working. My point is if you're cleaning your guns regularly, the product is essentially wasted on you and if you're not then I don't see FrogLube as being much different in performance than much cheaper products.