Gradius III was one of the first SNES shooters and to be perfectly honest, it shows. Graphically the game is fairly bland (although the same could be said of the coin op original), the sound is nothing special and when things get hectic there's some terrible slowdown. Regardless of these points, the classic Gradius gameplay shines through.
True to the series’ roots, Gradius III requires you to power-up by collecting the glowing orbs that destroyed foes leave behind. You will probably want to increase your ship’s speed initially, then take advantage of the powerful laser weapon, then start picking up ‘option’ upgrades. These are small indestructible orbs that follow you about offering additional firepower and protection.
The Gradius series has always been quite unforgiving of the novice player, but when you fully power up your ship things are quite easy. Most foes are destroyed quickly when you have the coverage of several options firing lasers. The misery starts when you make a single mistake and everything is stripped away from you, even your speed. This "rags-to-riches" game mechanic may put some off.
The level design is really good and plenty of variety is offered, each level having its own theme. The end of level boss battles are excellent albeit quite punishing. You will have to keep your wits about you until you figure out the best tactics to repeat in order to ensure success.
If you happen to be a fan of the Gradius series then you're unlikely to be too disappointed with this, even if it is a little rough around the edges. There are much better, more well-rounded shoot-em-ups on the Virtual Console at the moment so if you only want to buy one or two games in this genre you could probably do better elsewhere.