Not a RTS but a turn based strategy game with an excellent user interface.
Pro Constant updates and DLC's
The game was quite bland on release and subsequent DLC's and expansion have really breathed life into this game and brought on new features that have made the game in general more enjoyable. The free updates have also been well crafted and come regularly as does communication from the developers.
Pro Fully customizable ships
The game's ship designer is one of the most comprehensive and powerful ship designers in a 4X to date. Other than customizing the look of the ships you own, you can also customize the way they work.
Functional customization allows players to customize their ships to suit their play style. Either strap 20 engines to a ship to make it faster, or 20 sensors to make it useful in detecting enemy spies. The only limit is the player's imagination.
Pro Interesting building-placement minigame
Buildings can provide certain bonuses to other adjacent buildings. For example, putting two factories together nets a +70% bonus, instead of a +60% bonus that they would grant if they were far from each other.
This forces the players to think about how best to position their buildings.
Pro Deep strategy
On top of building placements and star base placement and order of updates made to starbases, there is a lot of depth to this title. Everything from whom you butter up to keep from destroying you to whom you ally with. The types of ships you build and what technologies your research is invested into and the order it is invested in.
Pre-planning for war by checking how many ships the enemy has and what technologies are being used on their ships so you can counter this with your own ship designs. In the early game this is even more important to use the ship designed to maximize an early advantage in exploration, colonization and star base building.
This is definitely one of the deeper titles out there in which you slowly uncover layer after layer of strategic depth as you become more familiar with the game.