I always wondered why MoO2 was never followed up with anything comparable by anyone. MoO3 was nowhere near the same experience and while I have enjoyed playing other 4X space games, this one really appealed to me with it's (obvious) tributes to MoO2 and detailed ship design and combat.
I have read some criticism that the game is too focussed on combat, but given the amount of detail that goes into the planning and building of your ships and ground forces, it is probably a good thing that people like myself who are looking for a decent combat space strategy game actually get adversaries who are very belligerent. Endless Space has many paths to victory... I have to admit I was normally more interested in combat.
Speaking of action, the space combat is great. You can design a variety of single or multi role ships that you can send into battle and see how your designs fare during the fiery cruxible of combat. It is immensely rewarding to see your crews do well, gain experience and even get medals for their performance in battle. The game is so detailed that it even keeps track of your fighter crew experience (which you can actually command in battle once they are launched).
Ground assaults are a little less detailed but still enjoyable enough.
The game has a few minor bugs that are being patched up, but the developer is so open to input from the community that I have to assume most will be resolved once they are flagged.
Solid effort and well worth the affordable price.