Restoring XtraBackup from MySQL 5.6 to MySQL 5.7 We are running MySQL 5.6 and taking backups using XtraBackup 2.4. We want to migrate to MySQL 5.7 using that same backup as we have datasets well over 600GB. 

Is it possible to do so and what are prons and cons that we need to worry about while we use the XtraBackup restore?
Xtrabackup is a physical backup tool, and is meant to backup and restore to the same MySQL (or MariaDB) version. It's not designed to work with migrations. It might work, it might not.

So if possible, if you want to restore the backup to a new instance, I think the best approach is to restore it to another MySQL 5.6 instance, and then upgrade that instance to 5.7 afterwards.