I managed to get my hands on an Open War deck this week and I thought I'd do a bit of a review as while it's designed for 40k you could feasibly use this for 30k too which I will get to later.
The box is of the same quality as the tactical objectives deck: sturdy, resealable and matches up with the astetics of the rest of the new releases.
The box itself contains 5 decks and a small instruction sheet that covers how to make use of the decks. In short, there's a deployment deck, an objective deck and a twist deck that determine the core rules. In addition, there is a ruse deck and a sudden death deck that provide additional bonuses for underpowered armies.
There's 12 deployment maps all in all. Some you may be familiar with from the core rules, others from expansions like Stronghold Assault or Sentinels of Terra. I can see some being a pain to set up like the old diagonal deployments but ultimately worth it for a more varied experience of the game.
Objectives are like the eternal war objectives but more options are available (12 rather than 6). Most depend on objective markers being placed on the board, others are kill point based, and there are a couple others that are a bit different. It's worth noting that tactical objectives aren't really directly compatible with these as they are - I'd be tempted to house rule some of the objectives victory conditions to make them compatible.
Twist cards add an additional element to the core mission - for instance, global modifiers to shooting, units taking damage from debris falling on the battlefield or even additional objectives for the mission.
Sudden death bonuses are very much like the ones in 7th edition and only come into play if a player is using an army that has half the power rating of their opponent - complete one of these objectives to instantly win the game (grabbing victory from the jaws of defeat).