Science fiction

My favorite genre is science fiction, I mean both movies and books. I have liked it since childhood when I spendt  (spent) a lot of time reading adventure, fantasy and science fiction books instead of reading the books, that was were my homework (from my teachers - although this phrase is not strictly necessary as this is implied by the word homework). My favorite author is Issac Asimov and I had have read almost all of his books. He had a specific style of writing that is really exciting. because It's quite hard to find a long descriptions of characters or the environment, so you need to use your imagination at full power. At the same time events happen so rapidly, and so many ideas are discussed, that you just need to take a break and think about it. My favorite book is "End of Eternity" by Issac Asimov and it hads  (has) significantly changed my mind. 

or you could say - My favorite book is "End of Eternity" by Issac Asimov and it had a significant effect on me  (how?, why?)

Really good - well done

Science fiction

My favorite genre is science fiction, I mean both - movies and books. I like it since childhood when I spend a lot of time reading adventure, fantasy and science fiction books instead of reading books that was my homework from teachers. My favorite author is Issac Asimov and I had read almost all of his books. He had a specific style of writing that is really exciting because it's quite hard to find a long description of characters or the environment, and you need to use your imagination at full power. At the same time events happen so rapidly and so many ideas are discussed that you just need to take a break and think about it. My favorite book is "End of Eternity" by Issac Asimov and it had significantly changed my mind. (Changed your mind how? This statement is vague so needs to have a more precise meaning because reading this book did something significant you said.)

Good writing, clear and easy to follow except the point raised.