Just been playing the demo; which consists of 100 turns, one civ (can't remember the name) and either the pioneering starting tech or a marine. I liked it, though some things kinda bugged me.
Aliens, especially at the start seem really powerful. My starting city was on a peninsular and just a few tiles south of me were about 10 alien forces and an alien worm, pretty much disallowing me from using a worker before I got the repel barrier and /or amassed some marines to keep them at bay.
When I right click somewhere but hold it down, the game sometimes doesn't recognise I'm still holding down the button and the unit moves, this can be annoying as sometimes I'll hold the button down to see how many turns it will be to move to that point, but because they've just suddenly moved, wasted turn.
The level upgrades don't seem particularly exciting, in Civ V you could choose between terrain modifiers, extra strikes, etc but with the marine it just seems an increase in strength or 50hp healed, is this the same for the rest of the units?