It wasn't Gradius but it was Einhander that got me into this type of genre!
Graphics 10/10: Remember, this is a playstation 1 game! The level of detail is impressive and I wouldn't be surprised if this was one of those games that truly pushed the ps1 at least close to the limits. From the background detail, to the massive bosses, the gatling gun revolving, the casings flying out as you're shooting,etc. It is all there along with the framerate even when things are chaotic.
Story 10/10: Why 10? Very simple....it's a shooter! Normally shooters have just about no story at all, except maybe, "you are the last hope on this uber ship, now go save the world." If anything, the story reminds me of Gundam Wing, except with more Kamikaze approach. I could see Squaresoft's hand in this (what the newbs know as Square-enix)
Gameplay/Value 10/10: It's fast paced, lots of action, lots going around in screen, multitasking of all sorts (switching where you're firing subweapon from makes a difference, top or bottom). Being able to pick from different ships is a welcome addition to shooters, but also having a couple more unlockable is even better. Although linear, it's nice to see secret paths and weapons. With all this said, replayability is obviously there (also the rating system is a nice addition).
Sound 10/10: The intro stage is too spectacular to top. With that being said, the music throughout was still top notch along with the boss fight music which REALLY felt like boss fight music (unlike final fantasy 1 rofl...same music throughout anyone?). The explosions are what are expected of them, along with each subweapon's unique sounds.
All in all, BUY this game if you can find it. I am praying it comes out on the PSN sometime soon.