Working out who has permissions to view what, has never been easier, this is the new generation Information Security tool for Salesforce admins.

For any object in an Org Model, open the tree and select a field. Select the "Field access by permission set/profile" tab in the right panel. Then click "Fetch field access data" to get the data.

You will get a notification when access details have been updated. You will see what profiles and permission sets (and how many) are associated with a given field.

The hyperlink icons will open the profile pages inside Salesforce Setup. If you roll over a listed profile or permission set, you will see a pop-over with key metadata about it:

Click on the "Show users with access" text button at the top to see how many users have access to this field, as well as their access type.