My local tesco has just put them on display today (to play with)! they are quite small, nexus 7 size, but looked and felt really nice! for the money i cant see how you can go wrong!
My Mrs recently bought a samsung Tab2-7''.
She is thrilled with it as it was bought for a pre Christmas trip to EuroDisney with G'kids.
My daughter is thinking the same as OP for her son at Christmas.
Tablet screen is more resilient for children. Ipod screens tend to shatter [older g'kid experienced this]
Ipod memory cannot be expanded but Samsung take mini card up to 32gb.
Many good reviews on amazon
Cost £129/39
Good cases available cheaply.