You can also navigate to a user and turn into them by selecting the Werewolf option in the More drop-down menu.
You may even transform into a user without Jira access. In this case, you'll see the Jira as if he/she would have access to it, you won't be able to create an issue though.
This may be useful if you are going to grant a user the access and are not sure about information he/she will get access.