My four-year-old son has not stopped playing with these since he got them a few days ago! He loves to build wacky vehicles with them (extra long crane boat, anyone?)Me? I love the case the pieces come in! It's easy for my son to carry and open and close by himself, but large enough to fit all the pieces inside easily - even if some vehicles are built! (We have not tried to fit the robot in there, but I think it would still fit.)The pieces are plastic, but well made. The magnets that hold them together are strong enough that the vehicles do not break easily, but my son can pull them apart with no problem.This really is a fantastic toy! I strongly recommend for kids who love vehicles and building things.