Kid Icarus is like a cult favorite in that many like it, but really it isn't some mainstream hit exactly. I still can't remember if I finished it, but my fiend claims I did finish it as a kid. That he watched me finish it. So i dunno. Maybe I used a code to skip some though.
Many speciulated that a Wii version of it is being made.
It's definitely an old-style game. Very unforgiving, very repetitive. If it came out today, it would be considered abysmally bad. I did have fun playing it twenty years ago, though (I've still got the cart). I'd recommend it if you like that kind of game and know what you're buying.
Yes, you can still drop shop keepers prices (not the black market guy though). You have to press A + B on controller one. Not buttons 1 and 2. Also, if you go to gamefaqs (I can't post the url for whatever reason, but I hope it's a good one!), they have some codes there to start you on level 1-1 fully equiped and powered up, should make it easier. Finally, older codes do not work.