Fun definitely comes closer than good. And probably closer than nice too. Nice feels a little bit more passive, you are more likely to see the enjoyment on someone's face with leuk than with nice.
Though fun might be slightly too active. I think somewhere between nice and fun. So enjoyable or pleasurable (buy that sounds kinda weird)
There is no exact match unfortunately.
Well I guess you could say it's a cool book. But cool can mean só many things it's not an exact match either.
A mix of cool enjoyable and fun haha