These two apps are both stylish and cool and work well for dd, she just plays through them, no need to choose levels or anything:
Count the Animals. You touch the black animals in each picture, something amusing happens and a laid back lady says "one", "two", "three" as you go. Only problem is that it goes up to twenty, takes a while.
Spot the Dot. App shows a coloured dot, then challenges you to find it in the next screen. Varying levels of difficulty, dd can't complete this herself. But it's lovely to look at.
These books have high quality interactivity (in my view):
Harold and the purple crayon. Magical. DD likes the porcupine a lot.
Sandra Boynton books. Carefully thought out "appy" additions to every page. You won't find them all on first read through.
Miffy's garden. Slightly less appealing for the adult, I have to say, but dd does seem to like it, there are constant invites to touch the screen to do a bit of gardening of your own.