Is this sentence a bit awkward?
Could you read the following? I'm sorry for the length, but I think context is needed.

　"Who is your favorite movie actor? For me, it is Daniel Day Lewis from the UK. I first watched him in the movie "In The Name Of The Father." At that time, I was really impressed by the film, but I didn't look into him in particular. Since then, I had forgotten about him.
　Last year, I saw him for the second time in the movie "My Left Foot." In this work, he played the character of Christy Brown, a cerebral-palsy-stricken painter who can move only his left foot. His performance was so natural that I became a big fan of his.
　What first surprised me was his stellar acting skills, but the second thing that surprised me was the enormous effort he puts into improving his acting. I was surprised when I heard that he had confined himself to a wheelchair throughout the entire filming to concentrate on becoming his character. (the following paragraph was omitted)"Q: Do you think the first sentence of the third paragraph is natural? Please help me! Thanks :)

Question

Is this sentence a bit awkward?
Could you read the following? I'm sorry for the length, but I think context is needed.

"Who is your favorite movie actor? For me, it is Daniel Day Lewis from the UK. I first watched him in the movie "In The Name Of The Father." At that time, I was really impressed by the film, but I didn't look into him in particular. Since then, I had forgotten about him.
　Last year, I saw him for the second time in the movie "My Left Foot." In this work, he played the character of Christy Brown, a cerebral-palsy-stricken painter who can move only his left foot. His performance was so natural that I became a big fan of his.
　What first surprised me was his stellar acting skills, but the second thing that surprised me was the enormous effort he puts into improving his acting. I was surprised when I heard that he had confined himself to a wheelchair throughout the entire filming to concentrate on becoming his character. (the following paragraph was omitted)"Q: Do you think the first sentence of the third paragraph is natural? Please help me! Thanks :)

Answer

For me, the most awkward section is in the first paragraph.

It's not clear what you mean by 'but I didn't look into him in particular.'  The phrasal verb 'look into' means to investigate, as in to look into a situation or a problem. You can't really look into a person.

The other problem is that the tense/time sequencing of  'Since then, I had forgotten about him' doesn't work. 'Since' refers to the time period up until the present, so you can't use 'since' for a finished period of time.

You could say, for example, 'After that, I forgot about him (for a few years)' in the past simple. Alternatively, you could relate this period to what happened last year by using the past perfect, and say, for example, 'I had forgotten about him until one day last year when I saw ...'

Note that you should also use the past simple 'could' in the following sentence about Christy Brown.

Otherwise, it's a nicely written piece of text.

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That sentence is grammatically correct and understandable, but it's not perfectly natural and it has too many surprises. In particular, you wouldn't use "improved" like that; it has a sense of becoming better compared to what it had been, which by implication is then not as good. I might write what I think you want to say as "What caught my attention at first was his stellar acting skills, but I then realised what an enormous effort he puts into his acting. I was surprised to hear ...".

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Thank you so much for your help, Simon Kinsella^^

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Just to add a small point:  I would make it "skill" not "skills". As an abstract concept the singular "skill" can still encompass the many aspects you mean, and it works better with rest of the clause.

"What first surprised me was his stellar acting skill...."

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@Emma Thank you very much for your comment =D