The Bayonet Attack in the Advance Caro. Is it good?

For those who don’t know what it is, the Bayonet Attack against the Caro-Kann goes 1.e4 c6 2.d4 d5 3.e5 Bf5 4.g4. I came across this recently and even managed to play it in a game, which was a quite fun change of pace from standard games against the Caro. But playing g4 so early just seems rather dubious. The main response seems to be Bd7, which looks okay for white, but other lines like Bg6 seem to allow black to reach immediate equality, while the g-pawn may become a weakness in the future. So simply what I’m asking is, before I make the Bayonet Attack my main response to the Caro, there’s one question that needs to be answered.

Is it actually good, or simply a dubious attempt at manifesting an attack in an otherwise solid opening?

it's not dubious. but I would prefer as white to play Nc3 first and go into the Shirov attack. There are plenty of games played to give an idea of the what and why.

It’s good, not the best, but it’s solid and Black’s position ends up pretty uncomfortable if they play perfectly and you can get an advantage if they don’t know how to equalize against it.