I'm assuming it's going to be Warcraft 3 in space with research bolted on, sound about right?
Currently, yes-no.
There are quite some differences in beta 2.
First, there is a culture system, which allows to culture convert enemy planets. Similar to the one used in GalCiv2.
Second, the map system is similar to the system used in Space Empires V, although warping takes time, the "field" contains only one planet/sun/asteroid instead of a whole solar system.
Third, you can form alliances with the AI.
Fourth, the resource system is different, with 3 resources, 2 of them mined on asteroids or refined via trade ships and one resource (credits) got via population on planets.
Fifth, the research system. Although it's more a research system like in a RTS like Empire Earth, than a full research system like GalCiv2 or SEV.
Similarities with WarCraft 3 are:
-Capital ships in Sins are like heroes in WC3.
-Ships and capitals have "spells" ie. buffs and abilities based on "mana" ie. antimatter. Spells can be auto cast.
-There's a population limit/ship limit based on planet upgrades (instead of space farms

)
-Ships have very unique roles, some are fighters (nearly melee combat, some are long range fighters, some are casters, etc.). You've got "peons" ie. construction ships that build structures (although the constructions ships are generated automatically).
-Diplomacy is similar to WC3 diplomacy. Almost no options and not much treaties.
Etc. etc.
All in all, Sins is no true 4X game, although it's more than just a RTS game. It's a hybrid for sure, although imho more on the side of RTS then 4X.