I loved the Richard Scarry books I had growing up (born early 70s in USA) and was excited to find this for my son. I bought it for my 4-yr-old, who loves it, but my 6-yr-old enjoys it, too.
We like reading the stories together but when the kids have time on their own to look at the pictures they spend several minutes poring over each page as there's so much to see and so many details to notice. As they get older they'll be able to read the labels all over the pictures, too, which will effortlessly increase their vocabulary-- always a good thing, in my view!