"This is a nice book."
Translation:זה ספר יפה.
Good question. Personally, I would use יפה for something aesthetically appealing, meaning that it's 'pretty'. But, if the writer meant that the book was nice in the sense of charming or delightful, I'd probably use נֶחְמָד or נאה. That's the problem with using 'nice' in English. It can mean many things.