In the past, all but one of the characters I've ever taken a role as I've been able to role play flawlessly. The one I couldn't get into was simply not the same as my personality. The characters I've taken all have similarities to me whether it be their intelligence, their emotional state, or their willingness to help others.

I know for some people it can be extremely difficult to take on the role of a character, even if you have a good understanding of them.

Well, it depends how easy you get along with the character, sometimes you can't get into the role of the characters when you get confused and you become unable to play your RP role. however it's never been harder than playing a character that has the same personality as you. what was the problem have you been having?

Most of my characters are based on characters which I have used a lot and/or they are based on myself. I find getting into character is something quite easy for myself due to how easy I can relate to my characters and remember their back stories and such as if they're my own.

all my character reflect at least part of my personality or how I act in a particular mood so I find it easy to get into character (sometimes).
The Just from Night Realm was a bad a example or my RPing skill her personality and past was particularly dark and I ofter found myself going out of character. This also happened in Zarpi. I found myself switching from her being hard and harsh to kind and far too caring.
I now try to keep my character close to my own personality so the are now days more kind-heated and caring.
so to answer the question "How easy or hard is it for you to get into the role of character?" I always try my hardest and I like to thing that I do it well however you'd have to ask my fellow Rpers for the final verdict.

It depends on the character. I often use OCs that matches me well but i also use characters from some animes who has some same personality as i am like Asch the bloody, he is hot headed all the time just like me..

So yeah

How easy or hard I got into my character?

Basically, it has steep curve to make the character "lives." It depends on how the one who takes control of character plays as him/her. And as far as I experienced, the hardest thing is to relate a character with others.

So, it's hard, I guess.

Since I often play as a wanderer characters, I think it's harder to take role as a character who lives and stays in one place for a long time. And I often play a "shady" character so the level of involvement difficulty into the character is "shady," too...

For me; the answer is both Hard & Easy at the same time.

The hard part for me is adding all the little details (personality, history, etc...). But once that is done, it's easy to slip into that character.

I don't think getting into the character is ever hard, it's telling the characters story that stumps me sometimes.