I rewatched this for the first time in years over the weekend in honour of its 50th anniversary, and I must say I think it's grown on me. The Showa films are divided into two distinct camps for me, the ones I grew up with and the ones I didn't. As a result, even the ones that might not be the best hold a lot of nostalgic value for me if they fall into the former camp, whereas films like Godzilla vs Mechagodzilla don't, and I tend to be less forgiving of their flaws than I am with others I grew up with.
When I first imported the 50th anniversary DVD years ago (*Godzilla's* 50th; has it really been that long already?!) and watched it for the first time, I remember liking it, but not loving it. And I think that's till largely where I'm at now, only I think I liked it more after this rewatch than I did the first go round. King Caesar holds his own against Mechagodzilla more than I remembered him doing, though he's still largely inconsequential when it comes to Mechagodzilla actually being defeated given how much of the story revolves around the characters trying to wake him/stop him from being woken up. And I'd forgotten how long that random musical interlude was!
That really could have done with another editing pass.
Still, the movie itself was fun! Some really nice location filming, and the aliens' base set was really cool too. The characters aren't really memorable or fleshed-out as well as those of various other films (though Nanbara was cool), but the film moves along at a nice pace, and actually feels kinda tense and high-stakes a lot of the time, despite the whole prophecy angle not really amounting to much and the aliens' invasion plan being as basic as they come. The score is cool, with both some memorable new themes and interesting twists on others, we get multiple monsters, fun action, and of course, the introduction of one of Godzilla's greatest foes in what is, in my opinion, the best version of Mechagodzilla ever.
Plus the movie is just so earnestly silly in places that you can't help but enjoy it. Kidnapping a human scientist who knows about "space titanium" to repair Mechagodzilla because the aliens don't have the manpower to do it themselves? Godzilla gaining super magnetism powers from lightning?! Sure, why not! I love it when such silliness is introduced and played straight like that, especially when it's just fun.
Oh, and the timing of this rewatch worked out pretty well as it meant I also recognised the main alien henchman from one of the last episodes of Ultraman Taro I recently watched as well! And he played an alien disguised as a human in that too!
So yeah, while it still might not be one of my favourites, it's definitely gone up a bit in my estimation now compared to what I thought of it back then.