Was the New Deal successful or not?
The answer to this is, to some extent, a matter of opinion or of how you define success. The New Deal did not end the Great Depression. If this is the definition of success, it did not succeed. However, we can at least argue that the New Deal kept the Great Depression from getting even worse. If that is the definition of success, it did succeed.
The New Deal was not able to end Great Depression. After President Franklin D. Roosevelt was elected and implemented the New Deal, the economy did improve. It grew at a rather rapid pace, although that is no too surprising given how low it had sunk by 1933. However, in 1937, another recession hit and the US economy slowed again. The economy did not get back to full strength until the US started to gear up for WWII.
This brief history shows us why it is hard to say whether the New Deal succeeded. One the one hand, we can say that it succeeded because the economy grew after the New Deal started. Things got better and, even after the recession of 1937, never got to be nearly as bad as they were in 1933. On the other hand, the New Deal did not (at least in the time before WWII started) get the economy back on track. We can say that the New Deal failed because the US economy did not return to full strength until WWII began in Europe.