I get why people don’t like it. The fact that he’s transmigrated is important, but not until the later books. He also doesn’t start making mistakes until later on. If you’re not into long, slow stories, this isn’t the series for you. But if you’re patient, you’ll love it!
The characters are well developed, and so intriguing. The worlds are also fully formed. I love how magic (and ki) works! Very cool systems!