In a nutshell, Momentics has been the defacto SDK for QNX since the dawn of time, and since then we have not seen much change. However since it was adopted as the default SDK for PlayBook over two years ago, we have seen leaps and bounds over what the tooling has been offering developers.
There is a lot of features that developers can get excited for that will make their workflow more efficient and less of a headache.
For starters, the installation process has been very much stream lined. According to the presenters, you can go from installation to having a "Hello World" app on your device in under 20 minutes. That is of course assuming you already have your signing keys installed. But if you don't, the updated wizards will guide you through the process.
In addition there have been many other aesthetic changes that will remove the guess work over what you are trying to do. The task bar has been greatly improved, cleaned from unnecessary and redundant icons, the font and highlight colors have changed for different snippets of text. Additionally, the QML preview pane has been re-worked to be more efficient and useful while developing your apps.
There are many many more changes and improvements, but we may have to wait for the official beta to release before we can get a full changelog.