Yes there are ways to download an entire S3 bucket. The latest AWS CLI tools released let you do it:
Before that you need to install these tools after that following command should do the job for you:
aws s3 sync s3://WholeBucket .
download: s3://WholeBucket/test.txt to test.txt
download: s3://WholeBucket/test2.txt to test2.txt
This is a one way sync that enables entire download. There would be no deletion of any existing files from the current directory until you specify it and it won't change or delete any files on S3.
You would also be able to do S3 bucket to S3 bucket, or local to S3 bucket sync if required.
refer this if needed: