The product description did not make clear what "jumbo" means. I expected an extra-large set of classic Tinkertoys that would work with the remains of an old set. But "Jumbo" refers to the size of the pieces, not the size of the collection. Big pieces are probably better for little hands, but we had been hoping that it would mesh with the odds and ends of old Tinkertoys that my husband had left over from his childhood.
That said, the toy remains a great creative do-anything building set, appealing to both the actual child (age 4, in this case) and the "inner child" (age 40-something). I didn't have Tinkertoys as a kid, but I sat down to play with them as eagerly as my son. However, we ran out of pieces all too soon, and I can see that we're going to want to supplement the set if his building craze continues. Also, one of the rods already has a splinter splitting off after one day of play, so I don't think they're as durable as a parent might wish.