I've been following this game since late 2013 when I got it, and since then it has turned out to be one of the best $5 I spent. Granted, that was on sale when it was in beta, so it's increased to 15, with a good sale going probably from 10-12, but the game is still a very good, if not an amazing buy.
Pros (As of May 13, 2015. Initial release):
+No issues with large lobbies anymore. Large lobbies are supported and quite awesome.
+Cool graphics. You can see every shot with very little FPS drop.
+From what my friends and I have tried and tested, the game seems decently balanced, from early rushes to late game turtle.
+Full, 26 piece tech tree that ensures that you can't simply rush in one direction without feeling the loss in other sectors. For example, if you singlemindedly rush lasers, you won't be able to build any defenses to counter the railguns that someone else built for half the cost and time.
+n-body physics on the main game map. Now I get it, a game about firing weapons through outer space better have a good physics engine, but this game is just awesome. Every massive (e.g. not weapons) body in the game exerts a force on projectiles, to the point where a gas giant that's behind your planet will mess up your firing arcs pointing in front of you. It can be frustrating, but its the best part and main attraction of the game.
+Non-instantaneous projectiles mean that you have to do some aiming at your target rather than just pointing your guns at them.
+Different level AI. Given that I haven't tried too many of them out, but still they offer training before you hit the scary players out there.
+Intuitive building mechanics. Everything makes sense pretty much instantly. You have two resources, balance them.
+Customizable lobbies. No more are games confined to 5 cities and 100000 minerals, but these are now modifiable for custom gaming. These, along with other things (like what weapons can be built, what size planets are, etc.), are nearly fully variable! This includes making games private so that only your friends can join.
+Turn timers. This was important, because people could sit in a game, raging, and never passing their turn. That would cause the game to stall out, but now with turn timers, that happens no more! Eat it, sore losers.
Turn timer only goes up to three minutes, which isn't enough in the late game.
Music is very good, but it is on loop and there isn't too much variety (About 8ish minutes of it, I THINK), but you can mute it and play your own in the background.
One game has a length of anywhere from 30 minutes to 3 hours, depending on how slow the starts are and how long it takes to get lucky with damage distributions.
-Has two decently sized bugs. One freezes the turn permanently if everyone in the game has passed except one. If that one person leaves the game instead of ending his turn, the game bugs out, sadly. The other is minor and easily fixable if you hit enough random buttons: the missile lock is funky. If you don't click on a target planet fast enough you screen looses its UI and you have to hit escape to go to the pause menu. When you come back, everything is fixed.
-Not a huge community. Before the game was fully released (i.e. beta) there was a very small community which could barely field a few pick-up games a day. Today there were lobbies open at all times though. Seems the release has breathed new life here.
-Game incorporates randomness in play affecting areas. Everyone's population and science increase at slightly different rates, meaning that you can never quite have the same opener/information on all players. On turn 10 of one game, a certain tech may be 1 turn research, where in another game it is 2 turns. Not huge, but for the hardcore people like myself, this can, in theory, hurt a few games in a hundred.
-Learning curve exists. While a pro to some people due to it's depth and skill based gaming, this means that you WILL lose your first game against random players. Hopefully you will be talking in chat the whole way with more experienced players who can teach you the ropes, but maybe not.
-Slight runaway leader scenario. The player with the better economy on turn ten will also have a better econ on turn 20, and 30 and 40... If you try and build a ton of railguns or lasers to hit the guy who is shooting you every turn with 10+, you are going to lose the war. If you try and fight fire with fire, you are going to get burned. Sadly, this is the most intuitive way to go about playing, and some people might call certain strategies unbalanced as a result.
All in all, if you like not-casual-but-not-super-competitive games about space, and/or artillery, and/or resource management, then this game could be for you. It certainly was for me. It is 100% worth the $11.99 on sale, and it's almost surely worth the $15 normal price. It's been a fun 80 hours, and I put in about 8 a week.
(Buy this game.)