Do what I do in terms of reviews: Look for confirmations on if your worries are correct. Is the AI glitchy as X's demo, or is it much better? Is the difficulty as off as everyone thinks? Are there game-breaking bugs?
Don't read it for their opinion, just look for facts. I never trust reviewers (after being one myself, not that I was paid off or anything, but I was always told for specific games "This publisher really, really likes us, add a few points here and there").
5 hour campaign? How much replay value? Tons. How much story that you'll actually remember? Laughable. Plenty of replay options: (Stealth/Melee only/Gunfights). Weapons to find, upgrade. Deniable ops (with randomized enemy spawns). Co-op campaign (another 5+ hours right there, not to mention how much fun you can have with just one other person). PEC challenges, too, for both Solo and Multiplayer.
Obviously not gonna convince you to re-order it on the spot, but if you really enjoyed the demo, give it a shot atleast. I've gotten way, way more of my money out of lesser-quality or lower-scored games than some of the newer ones with higher "ratings". EX: Dark Sector, Far Cry 2, Too Human (and I got these before they were as dirt cheap as they are now) just because I really enjoyed the concept. Not to mention here's a real shortage on third person shooters, and SCC will fill in a niche gap for some time, I imagine. (TPS fanboy

)
/wall o text