I played an early build of Sol Exodus at PAX last year. It looks good and has good control feel but the world was utterly generic and lifeless.
Talked to the devs that were there a bit about it but I have no idea if they made any changes.
It does feel generic and rough around the edges. There are 8 missions apparently and I've done 6 + Prologue so far, not sure if that's really 6 or 7 missions.
The story would be good if they had twice as many missions and made the missions longer. You go from Point A to Point F to Point M without anything in between. It seems to progress at a mile a minute without filling in any of the gaps.
At some points you are fighting and have no mission objectives, only simply to wait or mop up the seemingly constantly respawning fighters. There aren't that many different enemies to fight but they're reasonably interesting, especially those ADD's which you will hate with a passion.
I love the sense of speed in the game and boy do you zoom along. Your standard max speed is 475m/s and you'll pass a large capital ship in some time. Hit the afterburners and you'll pass it in a couple of seconds. In Freespace 2, arguably the very best game this genre has seen, left you feeling like you were hitting tab just for the hell of it at times. In Sol: Exodus, you really speed towards your destination.
The Gun lead guide seems to be completely broken but you'll pick up the lead time required quite quick.
TL
R. Short game, fun but not without it's flaws. Probably not worth the money (though I paid £15 for 6 hours of WH40k: Space Marine campaign and this cost me £6.99 for 3 hours so far)