What's changed

Getting a document directly has been changed from an int-int format to being a singular u64 integer, this is returned as a string for compatibility with languages where overflowing may occur when parsing (JS). This type of change has also be reflected in any other areas where you supply the document id.
Searching via mode=more-like-this has changed from expecting a query name called ref_document to just document and expects a document id.
Returned results now return a document_id instead of ref_address to make it easier to understand its purpose.
Specialised field name has been added _id if you define this in your schema, the system will ignore it and add its own.

What's been fixed

Searching by document / more-like-this queries now work, before this would lead to a panic if the searcher wasn't the original searcher that retrieved the document.
Getting a document directly no longer panics.