Super Metroid is my favorite game of all time, so what I'm about to say will have at least some bias.
The first time I actually played through Super Metroid was when I was 15 or 16, and the Wii had just come out much later. Despite having a good amount experience playing games, I died a number of times, and I got lost. It took me many tries to beat even the easiest of bosses, such as the Crocodile you have to shoot into the Lava. Ridley and the Ghost Ship boss were Hell for me. I even died to Monster Mother Brain a number of times. I remember when I finally got to the rainbow laser of doom, I almost raged quit because how many tries it took to get to that point. In the end, took me well over 10 hours to beat the game.
One of the main reasons I failed so hard was that I did not have all the beam upgrades, and my max ammunition was really low. The thing is the first play through, you are trying to figure out where to go, you many times forget about the areas before and think "oh, now that I have this speed boost, I can go back to X, Y, and Z area".
Playing the game a second time through, that's where things really shine, and you see just how well things work. Every time you get a power up, you use it right away to get an idea about how it works. When playing a second time, you've learned the in's and out's of all the power ups, you go through the areas again and mentally map what power up you need to access a certain area. You also learn that many areas with power ups do not show up on the map, and you must discover it yourself. Playing through again, you discover new places, get new power ups, and get through the game more easily.
Super Metroid is my favorite game because of this aspect. The game has the right atmosphere and starts with a world that seems barren. As you go through the game, you discover just how much is in it, and as you play more and more through the game, you discover even more about the game. The music nails the atmosphere of each area and really sends shivers down my spine. I've played through the game over a dozen times, and I even beat Ridley once without taking a single hit (got really lucky/was really in the zone). It's easy, but it really feels like a story unfolding as you go forward. I need to play a game where I try sequence breaking, which would add a different spin to everything.
Yes, as you play the game again, it becomes easier, and after the third or fourth time, it's child's play. However, I think most games become like that after a certain point if you've played it long enough. Heck, after playing God Hand on Hard Mode, I played it on easy mode using no God Hand or Roulette Wheel techniques, and it was easier than the first time I played the game on Hard Mode.