I'd say the Harmonica is a fairly easy instrument. You can learn just about anything you need to know to play a harmonica in about ten hours. The only difference between you and a professional player after that would be the amount of songs you know.
I'd also pick the trombone for being one of the easiest and hardest instruments to learn/play. It's easily one of the easiest brass instruments to learn, because the note progression is straightforward. And there are only seven positions you need worry about. Learning those seven positions can take a bit of time, but if you have a naturally good ear, it can be easily attained. Also it's an easy instrument to keep in tune, because if the tuning slide isn't well placed, you can move your slide accordingly. It's also can be very difficult. It's easier for other brass instruments to play quicker notes in succession, wheras a trombone player needs more practice and a faster arm to be able to do this. The higher up on the scale you go, the more you need to adjust your standard positions. The trombone is also one of the most versatile instruments. With a good trombone, you can get a great range. As a trombone player, obviously, my viewpoints are slanted, though.
Also one of the hardest instruments to play, from what I hear, is the French Horn. Because there are numerous partials for every position. But if played correctly, this can have a wonderfull breathtaking sound.
-MillsJROSS
I'd also pick the trombone for being one of the easiest and hardest instruments to learn/play. It's easily one of the easiest brass instruments to learn, because the note progression is straightforward. And there are only seven positions you need worry about. Learning those seven positions can take a bit of time, but if you have a naturally good ear, it can be easily attained. Also it's an easy instrument to keep in tune, because if the tuning slide isn't well placed, you can move your slide accordingly. It's also can be very difficult. It's easier for other brass instruments to play quicker notes in succession, wheras a trombone player needs more practice and a faster arm to be able to do this. The higher up on the scale you go, the more you need to adjust your standard positions. The trombone is also one of the most versatile instruments. With a good trombone, you can get a great range. As a trombone player, obviously, my viewpoints are slanted, though.
Also one of the hardest instruments to play, from what I hear, is the French Horn. Because there are numerous partials for every position. But if played correctly, this can have a wonderfull breathtaking sound.
-MillsJROSS