I'm able to bend notes pretty well now - it takes a while to get the hang of it.
The way I would explain how to do it is practice whistling while breathing in - it's the same tongue action as bending on the harmonica
I don't find it particularly difficult to learn - it just takes practice (as with everything I guess), but I pick it up pretty quickly.
I don't play it much but I know a few blues and country licks.
I love playing it around my dog - he goes nuts
A note about keys on the blues harp, most of the music you hear is done with the harp in a "crossed" mode. Meaning that instead of the exhale now being the root, the inhale is. Look it up, it's really intriguing.
I have a Hohner 1896 Marine band in the key of C. I went through a big harmonica phase several years ago after my first bone marrow transplant and it was an easy instrument to just sit and play without much effort physically. I got it as a gift while I was still in the hospital during my induction chemotherapy (I was in the hospital for 86 days for that - had to have two rounds as the first one did not do an effective job) and I started up playing while still there. While I still break it out frequently I don;t play it as much as I was for a few years. I always thought it's truly a unique and wonderful instrument that in the hands of a skilled player, comes to life like few others.