It's the rarity, Nav. The last truly good game in the 4X space epic genre was Master of Orion 2, released in 1996. MoO 3 bombed in a display of true shock and awe (this is probably the main reason why high-profile 4X games are such a rarity) and most other offerings in the genre are missing something. Space Empires (V) is probably the best of the bunch, but it misses flavor and polish. The GalCiv games are Civs in space - no tactical battles. Sword of the Stars on the other hand is all about battles; empire-building is nonexistent.

SoaSE comes to a starved genre at a time when it has no real competition. People tend to overlook flaws more easily in such a situation. And honestly, SoaSE has potential and the developers seem to listen to feedback. Something good may come out of this yet. Personally, were I a professional reviewer, I'd probably mark up the score just because the genre is in dire need of rejuvenation.

Space battles in SoaSE look okay once you get to the middle stages of a game, which unfortunately takes a couple of hours. There's a lot to improve though; right now ships aren't maneuvering around much and weapons fire (beam weapons in particular) looks oddly synchronised and too precise.

BTW, if you decide to play a proper game do yourself a favor and pick Fast speed. The game is very slow-paced even by 4X standards.