i was disappointed to see the stone age going out as well but i understand.
one of my sons was given 5101 from a friend for his birthday. its visually very attractive and has a nice look and feel - the hide over the skeleton has a lovely feel. but as others have mentioned, the play value on these sets is limited -even for a 6 year old who mostly enjoys setting up his kingdoms and only making very minor tweaks each day (i.e. changing a knight's position).
within about a week, he handed the set to me in the box and asked that i hold it for him. he cared enough to see that it had enough value to keep from his younger brothers, it just didn't have play value.