What's makes this instrument so special?

I’ve never played the harmonica before but would dearly like to learn more about this instrument. Music is a important part of my life. I’ve had piano lessons in the past but you can’t carry a piano in your bag so I thought the harmonica would be a good instrument but I need more information about it. I know that it comes in C or G, but after that I don’t know what to look for when purchasing a harmonica and where is the best place to buy one. Apart from a different key what are the other differences? What’s the best make what should I be looking for. Can anyone help me?

This is my opinion . Harmonica is the only instrument that produces sound either inhaling or exaling in it . It is Special because produces sad howling or mourning sounds mostly used for blues when played in cross harp position or second position wich is the same .But also you can play Jazz wich is more classy and dificult to achive at least for me . I personally don’t like sad songs played on the harmonica like campfire songs or things like that . Another aspect that makes it Special is that you can carry it with you everywhere and it is not too expensive so many people can buy and have one .

Harps come in 12 keys (and more), they can also be ordered in different tunings. Blues is usually played in the Richer Tuning, Country and Gospel is played with Country tuning.
Wood comb harps have a tendency to swell and the teeth grate your lips and tongue. High end harps are sealed properly and less likely to swell but the reed plates are still exposed and sharp on a beginners lips. Most Pros prefer Wood combs for a richer sound.
Plastic combs sound good, don’t warp or swell, easy to clean, and durable. I like the combs that cover the reed plates (but I am just intermediate).
Most beginner lessons are in the Key of “C”.

Oh yeah . I forgot to mention . I have bought some harps My first ones was a Marine Band in the key of A then I bought a Blues Harp In D A Honner Picolo Which has a lot of acoustic But it is very small diatonic I still have it. Then my son gave me a Lee Oscar in C . But so far the best one is a Special 20 in C that I got on Special for 20 dlls at guitar center This harp is just great . I remember I used to have a Hot Metal in the key of C and I was able to blow bend in hole number 10 which I can’t bend in any other one . Recently I bought a case of 7 harps called Piedmont blues but they’re not that good.
Honner Hot Metal in C is the only cheap Harmonica close to Special 20 in my opinion . It cost me only 5 bucks