There hasn't really been much change at all.
It's not really a major release, so that should be expected. It was just to add some improvements under the hood, not to the end-user
BTW, the biggest of which is this, IMO:
URL Filter API for Opera extensions
The URL Filter API for Opera extensions defines a DOM interface that allows extensions to add temporary rules to Opera's native content blocker. Rules added through this API are associated with an extension and apply as long as an extension is enabled. Once an extension is disabled or the browser is shut down, the temporary rules are discarded.
It defines the API that is applied to an extension browsing context.
An extension browsing context is a browsing context that implements the Opera extension interface (opera.extension).
See: URL Filter API for Opera extensions
Though it looks like there are still issues opera's extension implementation and the speed of javascript in them (extensions with extensive use of javascript are slooooooow). Also extension windows can't recieve right-clicks still, which is kinda lame at times.