Geppy-X is not a particularly good shmup. For most of the game it's too easy, and when it's not too easy it's just throwing unforeseeable gotchas at you - I guess the devs considered this fair game since you don't die in one hit, but it doesn't make for particularly engaging design. There's never really any point where you come out of a level feeling like the Lord of the Gamers for conquering a 100mph slice of hell, because that level simply doesn't exist in this game.
The good thing is that all this mediocre gameplay is couched in the most earnest We Love Goofy Giant Robots presentation you could ever want. You want an animated OP and ED every level? You got 'em. Eyecatch after the midboss? Done. Live-action ads for big chunky Geppy toys between those eyecatches? They're right there, go look. You want Zakus to shoot at? They're in there. You want one red Zaku that moves faster? Present and accounted for. Okay, logical conclusion, you just want a Char clone? You got one. You want him voiced by Char? Fine! Take it!
Sure, this is all just "hey, that's thing! I recognise thing!" stuff. Well, sometimes I like recognising thing, especially when thing is cool. Are there a million better PS1 shmups you could play instead? Undoubtedly. Do any of those have four discs worth of Obari-animated cutscenes and vocal tracks from the likes of Isao Sasaki, Akira Kushida and MIO? Fuck no they don't! put_geppy_in_srw!