My nephews got their first geo trax set 2 years ago for Christmas and every birthday, Christmas and just because chance we get, we add to it. Their first set of trains just barely died on them. They play with these ALL the time. They are hours and hours of entertainment for them. They were 4 and 2 when they got their first set and are begging for more this Christmas.
I plan on buying several sets for my own Son when he is old enough to play with them.