I think it is medium because it has some easy parts but some hard ones, too. So sometimes you know exactly where you have to go and sometimes you don't know where you should go next. But if your brother is only a little encouraged playing through it he will do it. With the saving possibilities of the Virtual Console it is fun.

Some passages are pretty hard, but overall the game isn't too hard imo. Now with the savestates in the WiiU VC version just about anyone should be able to beat it.

The bosses may seem hard to some but they all have that one weakness that when you find out, the boss becomes extremely easy, for example:

When you finally fight the SA-X, you'll notice that it puts off tons of damage, either by hitting you with a shinespark or by freezing you and firing a super missle, and it seems very hard at first, but there's a certain pattern the SA-X moves by, so you stand on the left side while the SA-X is on the right, you shoot it, it shinesparks horizontally at your direction, so you jump to the right and the SA-X is now on the left side, shoot it again, and it shinesparks horizontally at your direction, so jump to the left, and repeat until it mutates, then at that stage the SA-X mutant jumps at your direction, so move to the area it stood on before jumping and once it lands, you shoot it, and it jumps again, so you keep repeating until it's dead.

the game's overall medium at your first playthrough IMO, but it gets extremely easy in your next ones.

Haven't played it for 10 years... It wasn't very hard, but I remember that I needed many tries to beat the last boss.

I never owned the various portables. So I'm buying Fusion this weekend. Always love me some Metroid.

I recently finished it on 3DS, and I can safely say it is harder than Super Metroid. But I have finished that one over 10 times now so maybe I'm just getting good at it..

The boss fights are more challenging, but the general exploration is easier since you're mostly told where to go next (but it isn't fully handholding either). But even then, the general exploration is hard in its own regards, enemies hurt you much more than I can remember they did in Super Metroid.

The last boss and mecha-spider are quite tough to beat.
Actually it doesn't matter, as a whole this game is a masterpiece!

Easier than most metroid games. I chose easy.