The learning definitely slowed it down. I have not heard of people playing it in under 4 hours (at 4 players). There was quite a bit of rules referencing going on during the first play (combat is basically its own deck and dice mini game).
It is turn based, but you get to place 4 action tokens in sectors on the board (each player places 1, then it goes to the next player and so on). The actions are (move ships/attack, build/deploy units, research tech, collect special resources). Each faction has a set of 2 of each action token (8 tokens total). They are played face down on the board, so your opponents don't know which action it is. As you and your opponents play actions in the same sector, the tokens are stacked. Then during resolution, the tokens are resolved from top down. Lot's of strategy with which order you deploy your tokens and playing over the top of your opponents to preempt certain actions. Tons of fun. The resolution of actions takes place in turn order, but if it comes to you and your tokens are all buried, then you are forced to pass. Conversely, if you have multiple sectors with your tokens on top, you might take multiple actions before your opponents get a chance to act.
I hope that explanation makes sense, but it is just scratching the surface of the complexity. It does not however feel like a pure euro (Eclipse- with its cubes and resource/score tracks), instead it plays closer to Twilight Imperium, but with the 40k theme that really comes though. So infinitely better IMO.