I think I've played long enough for some first impressions…
At the top level of this game you've got a strategy map showing all the planets around four stars. You start off in control of one fleet and a giant ship building facility that can jump around with the fleet. The planets still loyal to the Colonies feed you tylium which you can use to build more ships. And you'll need more ships - lots more ships. The Cylons have quite a few fleets that will be jumping in and attacking planets. You can jump every turn but, if you jump in less than 3 turns, it costs you tylium.
When you encounter a Cylon fleet, you go into the tactical battle. That's where you'll be spending the bulk of your time. You'll set up where your fleet will jump in and decide what sort of munitions (missiles/mines) and fighters you'll bring. Then the battle starts. The battles themselves are played in 15 (?) second phases. You'll plot out where all your ships/fighters should go over the next 15 seconds, hit 'end turn' and off they go.
Ships are fairly complex with turning rates and firing arcs for different types of weapons. The battles are ALMOST fully 3D. Your ships can move up and down as well as turning right and left but they will always remain level - you won't end up with some ships pointed up and some down. Fighters can attack enemy ships/fighters or defend ships from missile attacks. Raptors have much less ability to fight but they do have several special options like boarding enemy ships - though so far I've liked the Vipers better.
The game has a nifty little feature that will let you stitch all the turns together after the battle and move the camera around 'Battlestar Galactica style' to watch it all play out. It's a lot more fun that I expected! Here's a sample:
There's also a little research portion to the game where you earn research points to buy new ship blueprints. Those same points get used to buy officers to manage your fleets so there's some deciding to do on that front - just don't expect big, detailed research trees.
The reinforcement pack DLC adds more ships to the game. The Broken Alliance pack adds a few more ships and more special story missions. Unfortunately, that means you'll need to decide if you want them not too long after buying the game, assuming you'll just play the campaign once. From what I've seen so far, the DLC is well worth the price even when not on sale. (I got the bundle on sale.)
P.S. The game starts up very quickly! It seems especially so having just played a lot of BattleTech.