Got it the other day and am really enjoying it. It feels like a proper evolution of GalCiv 2 (nothing I've noticed has really been omitted, with the exception of planetary governors but they're coming in the next patch).
I would say that it's not really the same as Civ 5. You actually have to place buildings on tiles on the planet (and each only has so many to build on) and their placement, as well as adjacent buildings, provide bonuses. There are also a lot more numbers to watchout for if you really want to be efficient. They also broke-up the tech tree to be more like Sins of a Solar Empire (you kinda have to focus on how you want to win, not just idly grab techs on a linear tree).
Of course, if you already know about the mechanics what I just said was pointless
Is it good? I like it more than the last one, and it's a close rival of Civ 5 (not a fan of the micro GalCiv has, nothing major). It still isn't enough to pull me from EU4, though