It works, with some caveats.

The app can be temperamental when registering, usually the biggest issue is you need to scan/read the embedded chip in the passport. That chip can be in different locations for different countries, the US is inside the back cover for instance. The photo scanning can be temperamental too. There are select airlines that work with the app.

The SmartPass app will allow you to bypass the first check in Security where they verify you have a boarding pass, after that you merge with all travelers for security and passport control. It is usually worth it.

As far as I know, the baggage drop is not implemented yet.