My 18 month old son got this puzzle for Christmas and LOVES it. He is obsessed with transportation objects, and the sounds make him giggle with delight. Yes, it will grate on an adult's nerves after repeated use! One major flaw is that any puzzle piece will activate any of the sounds, even if they don't match. On the other hand, this puzzle is easier for younger toddlers because the picture of the object is on the puzzle piece and the spot where it goes, not just an empty shape.
This puzzle is scary to me because one night after the toddler had gone to bed, I was locking up and turning off lights and the puzzle started making noises on it's own. After several different occasions on this happening at night, I finally figured out the if any of the pieces are left out of place, the sound is triggered by lights turning off. Freaked me out and it still does. Lesson: put the pieces away unless you want a fright at night!