Public product portal
With Suggested you can easily setup a subdomain to collect your user feedback, display your product roadmap and changelog.
Trello has not concept of a portal specifically designed for this. You can give users access read-only access to your Trello board, but this is a less than ideal solution.
Collecting feedback & voting
Suggested enables your customers to give their feedback on what features should be worked on using a simple voting system. This enables you to better understand which features should be tackled first.
Since Trello is primarily used for project management, it's like trying to fit a square peg into a round hole when using it to collect customer feedback. It alos has no support for sorting based on customer votes.
Suggested is specifically designed to enable you to show a public roadmap for your product development.
Though you can achieve the same thing with Trello with lists and cards, it's not an ideal solution.
Inform your customers when you've made changes to your product, or make other type of annoucments using a product changelog.
Trello doesn't support a way of showing the latest changes that have been deployed to your product in a graceful way.