Although deeply strategic, only enormous fans of the genre will enjoy it due to the absurd difficulty and bad interface.
Unlike Civilization, however, Endless Space is decidedly newbie-unfriendly. The deep strategic depth and enormous complexity would pose a difficult but fun challenge if they were not hidden behind one of the worst interfaces to grace a strategy game. It is never clear where you need to go to perform an action and the buttons on the interface are almost meaningless.
There are often several ways of getting to the same information, but it's always interspersed with additional details only accessible from that specific screen. The result is that you often find yourself looking at a screen that's telling you what you want to know, while at the same time wondering where the action you wanted to perform has disappeared to.
The game itself is absurdly hard, and takes forever to play. Games drag on and on and on, but not in a fun 'one more turn' way; instead, you end up spamming the end turn button trying desperately to make it finish. In the end, it's uncertain whether you'll even care about winning any more. This isn't necessarily all bad though, because if you aren't a turn-based expert, even normal level difficulty is extremely punishing.
If you are a fan of the genre, however, Endless Space may be for you. It offers vast customisation and huge amounts of data, letting you minmax the stats of your fleets and star systems as much as you want.
In short, I'd only recommend Endless Space to people who already know they love the genre, and who have a lot of experience with it. If you haven't spent months practicing this type of game, however, there are far superior options that are better executed and a lot more fun.