My twin DDs are 3 and we have 2 pens and 5 of the books!
We were lucky enough that their Nana got it for them for their xmas / birthday.
I think they're awesome (but am glad I didn't have to fork out the money). The girls are just at the stage of picking out random things on the page and aren't in the least bit interested in listening to the story
E will go through the entire book and listen to all the page numbers
ETA: My friends 4.5yo uses just the pen at night time to listen to stories in bed after the lights are out.
Edited by tishy