Q:Do like writing letters? Why and why not?

A:I don't like writing letters, because it is difficult and hard. I prefer to meet that person more.

=>I don't like writing letters, because it is difficult and hard. I preferred to meet them in person.

=> Corrected: The sentence is corrected grammatically. 

-대단했지. 나는 제주도에 갔었어.

It was great. I went to Jeju-do. =>It was great! I had a good time in Jeju Island.

-재미있는 방학을 보냈구나.

You had a fun vacation. => You had a nice vacation. 

-응, 너무 즐거운 방학을 보냈어.

Yes, I had very fun vacation.​  =>Yes, I had a good vacation.

=> Corrected: The sentences are corrected grammatically.