Yah, the campaign is painfully short.
I played through with Eldar and Spess Mehrens allready.
Gonna do Ork, Chaos, Imperialist Guards and Tyranids next.
The only really different Race in playing style are the Tyranids.
You get ONE HERO and that is it. Everything else you have to recruit on the way.
Well, not that i did anything else with Marines and Eldar . .
Basically took my commander and left the other heroes at home in exchange for more troops.
I basically only unlocked traits, not abilities, as far as possible. And when possible, i unlocked traits that would improve the Honour Guard if they were not deployed.
Space Marine Devastator Marines that do not have build up/tear down time for their heavy weapons is pretty sick, once you can field 4 or more of them.
Upgraded Eldar Weaon Plattform Teams are also pretty sick.