The PS3 version has high score online leaderboards for every planet, as well as fastest time online leaderboards for every planet. Outside of the leaderboards, I think you can see your high score on each planet when you go to the planet select screen and select that planet (or at least, I recall that it shows your high score, best time, and number of artifacts/gems collected; mind you, I haven't played since February).
You already finished the campaign mode? I think I spent 20 hours on the PS3 Gravity Crash, hoping to get the million-points Trophy, and only got about halfway through the campaign, and less than halfway to a million points, before encountering a mission that I seemed unable to beat without losing several lives (you can continue after losing all your lives, but your score gets reset). I don't think I suck at the game, either. It's really hard not to die in those tight spaces. Then again, the PS3 version doesn't have that anti-gravity ship.
Er, what does Gradius Galaxies have to do with vector graphics? Also, as a GBA game, it's highly unlikely to show up in the PS Store. However, I do point out that Gradius Collection is in the PS Store, and that's got Gradius I-IV and the PS1 game Gradius Gaiden, which was never released in the US.
By the way, djax, if you have a complaint about the game, e-mail the developer (Just Add Water) and let them know. Since this is a downloadable title, they may release an update.