If you've shared an asset for approval, you can see a list of all approvers and their approval status in the side panel of the asset.
Just hit the 'Reviewers' button in the side panel when in the playback screen. Expand it and you'll see all the users listed and their review/approval statuses.
Wipster will also send email notifications and activity feed notifications when videos and images are approved. For more on that see this article.