Our plugin integrates with Ensime, a headless Scala IDE server, to provide semantic services to Sublime.
* On-the-fly error highlighting
* Type-aware autocompletion
* Go to definition
We also plan to implement debugging support and already have a prototype of using debugging functionality of Ensime to set breakpoints and step through code. Currently debug mode doesn't support anything useful (e.g. you can't watch the stacktrace or values of locals), but that looks doable.
The main priority of the project is to retain incredible speed and responsiveness of Sublime. As far as the first impressions go, everything's fine - Ensime server typically starts within a couple seconds and almost all processing (except completions) is non-blocking and happens on a non-UI thread. Everyday use of the plugin will validate this claim, but in any case performance is not something we're going to sacrifice.
Downloads and installation instructions: http://sublimescala.org
Issue tracker: https://github.com/sublimescala/sublime-ensime/issues