Now, whats a Preview Release?
We threw everything half-done out what isn't either stable or is now still in progress, tested it and put in a package So basicly you could also call it Fleet Operations 2.9 Beta or something.

Why a Preview Release, why didn't you wait until everything is done?
We want all the new features and races tested so that v3 will be bug free and rock-stable (though as far as we now they run fine in the PR).

What are the difference between the PR and the upcoming final release?
Unlike v3 final, the PR does NOT include:

• Borg
  The Borg are not included in this Version. We are still working on a
  full scale redo with many new features for the final Version 3.0
  release.
• Noxter
  The Noxter are not included in this Version. There were some severe
  bugs within the Beta 2 Noxter. The Noxter will of course come back
  after a rework in a future version of Fleet Operations!
• Special effects
  Several special weapons effects, map objects and damage effects are
  still placeholders and will be replaced and advanced for the final
  Version 3.0 release
• Starship and Station models
  Many Federation Units got already replaced to fit the new Version 3.0
  graphic look. You will still find some old models along with the
  new ones in this preview.
• Non Player Races
  The Tholians along with a few other NP forces are ready to be fought
  against. Prepare for them in Version 3.0
• User Interface Elements
  Several improvements to the UI will be released in Version 3.0
• Voice Sets
  Some unit sound sets for the Dominion are not yet done. Another voice
  set contest is planned before release of final v3.0. Check
  for news on how to participate and maybe your voice
  will be heard by all Fleet Operations players after the final version
  is released.
• Dominion Music