My kids are 5 and 4. They can negotiate the standard brands of glue sticks but cannot open the staples brand glue sticks by themselves. Other than the glue works as well as any other.
Bought the Staples glue because it came in a purple container; that's all my preschooler cared about the packaging. After using it it is a nice product.
I wish they came in a bigger size run out too fast. Mostly use them for Elementary Special Needs students so they can see where the glue is. Also use them in home office. Love the color.