overread: ITs a long way from homeworld!
Fleets are smaller and need to be used more tactically since ships generally take a while to build. Movement (from what I remember) is fully 3d, but very much like homeworld its not that much used in 3D movement - mostly just 2D will work well enough (sadly a limitation of RTS games on a 2D moniter ;)
Generals also form part of your setup and you can put them incharge of ships to give bonuses to performance - carefull if your ship gets blown out (I don't think they always make it to the esecape hatch!)
There is an extensive research tree - with a lot of options from planet and government advances to ship weapons and spy methods.
Spies are a key aspect and one should always have at least one or two to give havok to the enemy and protect against the enemy's own spy activities
Planets are not complicated to run, but are a key part of the game, as is holding them. There are also governers to consider putting in charge to give boosters to certain aspects
Resources are more limited and much come from planets, but there are asteriods to mine for additional resources.
ITs 100* more pretty than Homeworld 2 - heck explosions are a joy to watch :)

ilves: Sooo... MOO2 but real-time and 3-d?

Wishbone: From the screenshots, it looks an awful lot like Homeworld.

Fenixp: Yeah, there's blackness, there are stars and there are ships, of course it looks a lot like homeworld! :D

overread: Sorta - if you ever played Imperium Galactica 2 then its similar, but with a more RTS line to it - that is units are now important, fleet control is more complex that rushing all units into one big motherfleet (ok this part might be similar ;)) whilst the basebuilding aspects have been toned down for Heagemonia. This helps it be more streamlined and also play smoother in a multiplayer environment I think.
IG2 was a pain in MP as sometimes things would go super slow (Start) and then later on managing planets, ships, research, spies - it was a lot, though you could automate quite a bit - ok when you had a pause button but not in MP.

Fenixp: Don't stop talking about Haegemonia because of random encounter: Troll!
I've played it back in the dark ages, when I didn't even buy original games (dark ages ineed - yes, they're not SO far back in my history :D ). Considering how much time I've put into pirated version of this game, the least I can do is buy it from GoG.

Freyar: After the disaster that was Genesis Rising, I was skeptical about giving this one a try, but I grabbed it anyway.