Marcelo - yes, I took my test last weekend, and passed with a score of 96%.
It's fair to say these sample questions definitely helped!

This is valid. I passed today! About 3 questions has wrong answers in it though. these questions have been covered by others here

Nathan, have you taken the test yet? When do you want to do it?

Another wrong answer:
If an application is storing hourly log files from thousands of instances from a high traffic
web site, which naming scheme would give optimal performance on S3?
The right answer should be: HH-DD-MM-YYYY-log_instanceID
HH will give some randomness to start with instead of instaneId where the first characters would be i-

Another example of incorrect answers: 'Which of the following services are key/value stores (choose 3)' - SNS, S3, DynamoDB, Elasticache, SWF
The correct answers are S3, DynamoDB and Elasticache
But it claims the correct answers are SNS, S3 and DynamoDB. This is incorrect!

Some of the 'correct' answers and wrong! EG: 'What is the maximum number of S3 Buckets available per AWS account?' - the correct answer should be '100 per account' but it incorrectly says '100 per region' is correct.
(ref: https://docs.aws.amazon.com/AmazonS3/latest/dev/BucketRestrictions.html)