On one hand the frontier was successful because he made high level black appointments which meant he was improving civil rights. He also increased the minimum wage to help the poor and gave money to businesses to create jobs, both of which benefited people who needed more money.
Frontier not successful
On the other hand the frontier was unsuccessful because many of his actions were blocked by congress. The congressmen were worried that Kennedy was securing civil rights too quickly, and as his actions were blocked, they had no effect so they were unsuccessful. His minimum wage raise only helped people with jobs so the really poor gained nothing from this.
Overall I think that Kennedy's New Frontier was unsuccessful because even though he had good ideas and tried to pass laws, he couldn't acheive what he wanted to before he was assassinated.