Finally, a thread I actually know something about.
Yes, I purchased Endless Space when it was in the beta. If, like me, you liked Gal Civ, Master of Orion, Stars! and other turn-based space 4X type games, Endless Space will likely give you a few hours of fun.
I haven't played it in a few weeks (life getting in the way of gaming), but I enjoyed it when I did. It certainly is nice to look at, design wise. Very simple, elegant even. The AI certainly gave me a good run for my money, though, in the version I played, I found that, overall, the game did not allow much flexibility for different strategies, so games tended to feel the same after a while.
I think that, if you are a patient gamer who enjoys longer, strategy-oriented games, you would enjoy ES. I can't speak to Multiplayer, since I didn't try it. Also, I would say that you should try it if you get a chance as the developers are clearly very interested in improving their game and I would expect that the current version of the game is probably much improved over the version I played last.