Beta 3 especially seems to have stability issues. Application quite frequently stops responding. For instance when the connection has been lost. (We use a VPN to our development server. When this VPN connection gets interrupted the database connection ends) When trying to reconnect the application freezes and I have to force close. Sometimes this happens when executing a query.

You can go to Preferences > Oracle / Connection, and enable the "Check connection" and "Check all sessions" option. This will also act as a keep-alive for sessions that might otherwise time-out.

I had enabled these options for beta 2 because I was hoping it would solve those vague freezes. It didn't, maybe even worsened this.
I want to emphasize that we use a VPN in order to connect to our database environments. And I'd made another thread about Execute query "running" but not in database. Behaviour looks similar to this.