My son LOVES this puzzle. He has done it many times. It is large and has nice detail. And of course, it's Thomas and his friends. What little boy could refrain from jumping right into that puzzle completion project.
My son loves this puzzle challenge. There are two levels so your child can feel a sense of accomplishment with the first level but also a sense of challenge as s/he grows. The flip side of the cards requires the child to place the geometric tiles without the guidance of outlines. It's also pretty portable so you can bring it in the car on trips. Or even on the airplane, which I've done, although it is somewhat bulky.