So, I've just bought Rebellion and played around 8 hours. Have been waiting so long for Stardock to release an update to Sins or a sequel and my first thoughts on Rebellion are great. Although the game hasn't changed that much from the original or Entrenchment/Diplomacy it adds a new depth of gameplay being able to play the different factions.
I rarely play on-line and tend to play mainly comp stomp games although I think the AI in Rebellion has been altered from that of the last two games. I actually think they've made the AI a bit dumber, from the last few skirmishes I've played the AI seems to hang around their own planets and not follow all out attack plans like they used to. The level of AI also seems to have been changed, on Hard it seems to easy to defeat the AI while on the next step up on Unfair it seems the AI is too powerful. I used to be just able to defeat Unfair opponents and was a pretty even match, however now it seems a bit unbalanced.
Also noticed a bit of a slowdown due to the massive amounts of ships now, I think the corvette adds to this due to its numbers. That kinds of limits me to playing smaller maps and less AI even though my comp is a reasonable spec with a 2.6ghz quad core and 9800gt (yes i know its old but its capable!).
Anyway I think Sins of a Solar Empire: Rebellion is pretty awesome and adds more gametime to the SOASE series. Hopefully there will be an overhaul in the future and we will see a completely updated and different Sins though!