I see Sins of a Solar Empire as being kind of like... Supreme Commander meets Homeworld.
Is this a good thing? YES!
Supreme Commander is a fantastic game, due to the pure scale and strategy involved in the gameplay. Only problem is, most people don't have the PC to run it!
Sins has the benefits, without the pitfalls. Sins runs like a total dream on my PC, with all the depth of strategy and scale of Supreme Commander. (and the handly camera!)
Homeworld is also a fantastic game and I love the beautiful spacebattles and intelligent targetting of ships.
Sins has this AND empire management.

I like zooming in and watching the battles happening, without having to do too much, but still being able to "micro" my Capital Ship abilities.
I love the Pirate Homeworld (base?), it looks awesome.
I like how there are many branches for you to take in Research, resulting in some seriously different playstyles depending where you go first.
I like being able to manage multiple planets and expand, upgrading them and defending them.
I like the fact that, the more planets you control, the less they buff your income due to them being further from your homeworld. This helps to avoid the "I've got more planets then you, therefore I win." issue.
I like the handy GUI and the way it creates a new GUI icon for each control group you assign.
I like the fact that just clicking on Crystal or Metal extrator places it in the correct place automatically.
I like the buildings like Broadcast Hub (correct name?), Trade Port and Refinery. I like the way they add different aspects to the game other than just pure war.
I like how the different ships have obvious different uses, such as the LRM frigate seem like they'd be a good ship for attacking Defensive Structures and Capital Ships.
I like the Scalability, not only in speed, but in size. Small maps --> MASSIVE MAPS... Few players --> LOADS OF PLAYERS... So it caters for everyone.
What do you like?