Story: I really don't know, I never had the instructions. In game you learn that you're the last hope to take down Andross, you and your wingmates, but no explanation is made of why or what in-game. Not much to the characters either.
Characters: Fox is the leader of the flight and the one you control, meaning you learn the least about him since it's everyone talking to you. Falco is your main wingmate, he's the best of the squad besides you and as a result gets into trouble the least, he's also cocky and won't thank you when you save his life. Slippy's rather awkward and gets into trouble easily, perhaps the worst of the team. Peppy is more of a father figure to Fox in later games, but in this one he's just the fifth wheel out of four, little to no personality besides the never-ending "Stay in formation" during the training mission, and as a fighter is better then Slippy but worse then Falco. The general dog (I'm assuming it's Pepper but his name isn't mentioned) gives you your mission before every level, and Andross is the main bad guy. The other enemies don't have names except for some bosses like the Rock Crusher.
Gameplay: You fly a ship through space or above a planet in an on-rails shooter, you can speed up or brake but can't stop. You can move up, down, left or right in a variety of locations, but the goal of each level is to get to the end without getting kileld and beat the big boss, which is usually a big ship of some sort. You get bonuses for killing everything that's hostile, but it is possible to go through the level without killing anything if you feel up to the challenge. Your basic blaster is powerful enough to kill many enemies in one hit, and it can be upgraded as you move along. Not all enemies are destroyable though, some are obstacles you must avoid, adding in more strategy then might be wanted when you have a second to guess where to go. You also have missiles you can fire, which are limited and slow, but do great damage, they're best left for later bosses.
Power-Ups: You can upgrade your blaster to fire double shot, and then plasma shot to kill most enemies in one hit. There's an invisibility ability to make you unable to be hurt by obstacles or enemies, but only temporarily, and missile power-ups to increase your missile count, plus various scattered rings that refill health and sometimes serve as checkpoints.
Unlockables: Not really any, but there were secret levels in the game and even a bonus ending if you knew how to find it, but those were hidden well into the game. Besides that there weren't any unlockables, no new ships or characters to play as.
Difficulty: Hard. Not easy. Call it what you will, this game was a challenge. Beating level 1 (Easy) was hard, beating level 2 (Normal), was harder, and beating level 3 (Hard) was a huge challenge. Why? Something about the sheer amount of enemies trying to kill you combined with the amount of skill you need to dodge everything thrown at you and shoot back. The ability to deflect projectiles (Double tap R or L) made it easier to dodge, but harder to steer or fight back. And the final boss was really hard, Starfox is one of the few series that had a truly hard final boss in every game, not to mention great bosses all-around. But not impossible, eventually you can beat it.
Technical Details: The graphics are the biggest draw to this game, and they look good, albeit simple. The music is good, but not spectacular, though it does fit the theme. The sound effects are better then the music.
Replay Value: There are three stories to play through, which start and end the same place but give you different levels to go through as you progress and give a different ending video. There are also the two bonus levels, which are likely impossible to find without some form of guide, and any challenges you make up, which are usually feasible. No multiplayer isn't much of a loss since there's not much you could do with multiplayer besides split-screen fighting, which would have been a
challenge for the SNES hardware.
Final score breakdown:
Sounds and Music: 7/10
Replay Value: 8/10
Great looking, good use of Mode 7
Plenty to do
A good challenge
Boss fights are well thought-out
Obstacles require trial and error at times
Music and sound work, but aren't memorable
For a game with nothing but on-rails shipfighting to do, it does that extremely well, you won't find a better one unless you find one with a better soundtrack and a better story. Other then that there's not much you can add to it.