I wouldn't say it's a bad thing. If it works for you, good. But if the book is in your native language, my advice would be read it in that language.

I tend to favor my native language for a few reasons though. I live in a foreign country so it helps me keep in touch with my language. Also if the book is old (like 100+ years) a translation in my language would make it easier to understand. Finally if it's an audiobook, I find it easier to follow without zoning out if it's in my language.