To me, it's a System 11 ruleset in a DMD game. I have a review of it up on IPDB where it ends up with a 6 / 10 for me, but I find that I rate games differently than my buying habits... I own at least five or six games that I rated below that, and LOTR, which I gave a 9.6, I have no interest in owning of those ever.
For Godzilla, I don't like the audio at all, but the shaker is integrated into the game so well, I feel like that evens out. The gameplay is dominated by just a few shots because there really isn't that much you can shoot at.
I would pick one up if it fell into my lap for the right price, but I wouldn't seek one out. In a large collection, I think it can hold it's own. In a small one, I don't think it's worthy.
And, for Sega cred, VND is one of the best games ever made and mine will never leave, and I also own Batman Forever, Baywatch and Starship Troopers. X-Files is one of the worst games ever made, but that has nothing to do with the name on the backbox.