I chose this for my son's 6th birthday, based on reviews, and was not disappointed.
At first, my son complained because the block of plaster is very hard and takes a lot of hammering, with patience and persistance. This is one of the reasons I chose it for him, because I thought it would do him good to have something that might teach him to persevere. It needed my help to begin with.
However, once he found a bit of his first crystal, he was hooked. He still needed a bit of help, but eventually, he was stuck in, hammering and chiselling for hours and whooping with joy every time he found a new crystal, or got one out. He was delighted with his little bag to put them in and couldn't wait to show his finds to friends and nanna. He has even asked me if he can have another one for Christmas so he can collect more crystals.
I am very impressed with the quality of this toy. The crystals look very nice and all the tools provided are great and can be used again for something else. There is a lot of dust made, so watch out. We set it up on a tray, on a table in the garden on a nice day, and the tray had to be emptied out frequently.