For the past two Salesforce release cycles the Lightning Data Service (LDS) has been in developer preview, but starting in Summer 17, it moves to Beta. The biggest thing to be aware of is that if you have created any code using the LDS, the markup will need to be changed. Prior to Summer 17, the LDS used the force:recordPreview tag, but this has been replaced with force:recordData.
If you have created code using the Lightning Data Service when it was in preview and named force:recordPreview, you will have to change your markup before that code will work in a Summer 17 org.
So what is the LDS? (you may be asking yourself)
The LDS is on it’s way to becoming the standard controller (used in Visualforce) equivalent for a Lightning Component. It makes working with data in a Lightning component super easy (as in all you need to do to use it is add a single line of markup code). No Apex code is needed.
Another thing that makes the LDS so cool is that all Lightning components that utilize the recordData tag will have access to a shared data cache. This ensures that they return data as quickly as possible.
If you have not yet checked out the Lightning Data Service (LDS), this is definitely the time to do so. And if you are interested in seeing an example of how a Lightning Component can be greatly simplified using the LDS, go over to Pluralsight and check out my latest course titled, Customizing Salesforce with Lightning Components. I have an entire module dedicated to Working with Lightning Data Service.