You’ve already read the book, hence, past tense.

Use active voice to make your statement less wordy, less boring and more straightforward.

The tense is wrong. Unless you are speaking about it while you are currently reading it, you would say that you found it to be very straightforward.

Better composition of said thought:

I didn’t find this book to be confusing, rather it was very straightforward….” I would add something after straightforward, like why that was a pleasant experience, how it helped to communicate the author’s ideas without excessive details interfering or whatever your impressions were.

When you have a comma like that, look at both clauses. If they are both complete sentences, then you have a run-on. In this case, you do indeed have two complete sentences.

To make it grammatically correct, I suggest a period. Or at least a semi-colon.

“There isn’t anything confusing to me in this book. I find it very straightforward.”

“There isn’t anything confusing to me in this book; I find it very straightforward.”

Try one of those.

The first is passive voice. The bad use of a contraction is informal at the least. There is a dangling modifier. “in this book”

There isn’t anything confusing to me in this book,

The second sentence is OK if it wasn’t tacked onto the end of the first.

I find it very straightforward.

If you are still reading the book and the present tense is correct

1. No contractions in a formal essay, i.e. you cannot write “isn’t.”

2. Normally you don’t speak in the first person, i.e. you should not use the words “I” or “me.” If that’s what you’re supposed to do, then just ignore this comment.

How about something like:

“This book is not confusing. In fact, it is very straightforward.”

It should read like this ” I find everything confusing even books, so I post retarded questions like this on yahoo answer.