Pro Leisurely real time combat
The large scale of the game controlling fleets in may solar systems allows for a leisurely pace to play, which makes for worthwhile way of controlling ones ships across multiple places. This makes for less stress in the game due to how intuitive and evenly paced the game is.
Pro Very distinct races
The game has three main races - Vasari, Advent and TEC and they offer completely different playstyles. TEC have the best economy, Advent's strength lies in their abilities and how they can be synergised and Vasari focuses on their tech - the incredible Orkulus starbase and Warp Stabilization.
Pro Large scale space combat
Sins games range from 7-130+ planets and hundreds of ships per player, all in real time, giving the game a fairly unique scale. Battles can wage on multiple worlds simultaneously and thanks to Sins UI and unit AI you can successfully manage fighting major battles, keeping your economy and ship production rolling, and development and research all at once (with some practice of course).
Pro Diplomacy used in a smart way
Different factions will send you quests that may effect your relationship with other factions meaning you will have to choose who best to make a friend or make an enemy when taking these missions. This bit of strategy can greatly change the outcome of a game depending on how well you have chosen who to help and who to possibly make angry.