Check out our blog post we just posted:
Collector for ArcGIS v10.3.4 is out | ArcGIS Blog
This is a minor bug fix update that addresses a number of customer reported issues on both the iOS and Android platforms.
We are also actively looking for customers willing to beta test high accuracy field data collection and anyone willing to share their stories of using Collector for ArcGIS. Email us at Collector4ArcGIS@esri.com and let us know if you want to beta test, how we are doing, and share some stories!