According to a recent study, reading a book with your child every day makes a huge difference:

"[A] study revealed that “students whose parents reported that they had read a book with their child ‘every day or almost every day’ or ‘once or twice a week’ during the first year of primary school have markedly higher scores in PISA 2009 than students whose parents reported that they had read a book with their child ‘never or almost never’ or only ‘once or twice a month.’ On average, the score difference is 25 points, the equivalent of well over half a school year.”

The study also said that it really helps to talk with your kids about what they've done during the day, and to tell your kids stories. They said that just "playing" with your kids isn't as effective, at least when it comes to reading comprehension skills.

http://www.nytimes.com/2011/11/20/opinion/sunday/friedman-how-about-better-parents.html

Really interesting stuff!

Do your kids like to read books? How old was your LO when you started reading books together?