Since the 0.5.2 build was published last month we have been working with Coatsink to patch keys issues introduced in recent builds and recent versions of Unity and are publishing the first batch of optimisations, fixes, and other modifications in the 0.5.3 beta.
The 0.5.3 build has numerous bug and stability fixes but we are still working to fix issues with the multiplayer camera, vents glitches, costume exploits and conflicts, inconsistencies with lift forces and concussion times and expect to push these fixes to Steam for testing in coming builds.
We have also started work on a full rebuild of the UI, localising for multiple languages, and a more standardised testing process (with additional resources working with us to identify and fix issues).