You write answers to this kind of question in three parts:
Start by saying: 'In some ways the New Deal can be regarded as a success...' and then talk about all the good points/successes.
Then miss a couple of lines and write: 'However, in some ways the New Deal has been said to be a failure...' and then list/explain all the criticisms/ failures/ bad points.
Then miss another couple of lines and write: 'Therefore...' and put your opinion, based on what you have written. Explain WHY you have come to the conclusion you have come to.
There is no 'conclusive answer' to a question like this - only YOUR conclusion based on the argument you have presented.
To make your conclusion as good as possible, try to:
1. avoid saying 'successful in some ways, a failure in others' - this is merely repeating your essay! Try to come to a conclusion one way or the other, and your conclusion will explain WHY you think one side is a stronger arument than the other.
2. avoid simply summarising/re-hashing the evidence you have already presented in the previous two sections. OF COURSE you will have to refer to them! But try to 'save' a really telling piece of evidence until the conclusion, and then produce it, like a rabbit out of the hat, to 'prove' that your decision (success or failure) is the right one.
This webpage does all the hard work for you.
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This webpage tells you about the measures of the New Deal.)