Developers have fixed a lot of bugs with this release, including a nasty little one that could cause unrecoverable database corruption. If you're using version 10.3 you'd best upgrade in order to avoid potential corruption issues.

However, version 10.4.1.3 is billed as a features release, which introduces a number of new capabilities like these:

• With asynchronous replication, you can maintain an up-to-date copy of your master database on a different host.  Even if the master database crashes, you can perform failover to the copy and keep right on serving client requests against your database.
• New security features mean that shutting down the Network Server now supports user authentication, and credentials are required when authentication is enabled.

New capabilities in the SQL (Structured Query Language) department provide:

• The ability to pose sophisticated queries against in-memory collections, flat files, web resources, non-relational databases and more using table functions and standard SQL.
• The use of table functions to import data from web feeds, sensor logs, and other relational databases with more efficiency.
• Unique constraints on nullable columns, a SQL ROW_NUMBER() window function, (for an empty, inline window specification), and bracketed comments like /* ... */.

Performance and memory usage have been supplied with a new buffer manager that provides better concurrency. In addition, there's now a statement cache, caching of isolation level and caching of current schema in the client driver. 

For another take on the changes that come with this release, go to the notes.  You'll also find details on the bug fixes.