It is very similar to BFG with significant national/faction differences but some elements are streamlined. Absent close in weapons, ranges are unlimited but everything depends on achieving a firing solution which is determined by adding the firers electronic skill (scan range) to the targets electronic footprint (size plus activity) and subtracting any special EW tricks. Lots of special actions are available but many can generate a bigger EW footprint. Ordnance (fighters/bombers/torps) are strictly limited based on the size of battle (very valuable and not available en masse) thus the game moves sharply without carrier/aircraft clog that can curse both BFG and DW.
The game is totally focused on planetary rationale in that missions are invasions. bombardment. raids and defense and ignoring objectives will almost always result in failure. You can rarely kill your way to victory while ignoring objectives. This makes special assets - troop ships, bombardment vessels, landers - very valuable and in need of both protection and careful use. They (along with carriers who mostly cannot get in fights and live long except for the very largest) have to get to objectives while keeping out of the way of the other fellows big nastys.
The factions are (rough rough analogs) with UCM = Imperials (basic humans, not the best tech but very shooty), the Scourge = Tyranids (parasites with essentially semi-organic ships) close in brawlers with some stealthy stuff also cheaper but generally a bit fragile , Post-Human republic PHR = Space Marines/Adeptus Mechanicus , tough with better tech but fiddly to play (broadside ships almost age of sail thus maneuver dependent. Shaltari = Eldar, significantly higher tech, more fiddly rules, freaking Elves, have not seen them play but tech/nasty/fragile.
All in all I've been impressed and the models are first rate and then some.