They forgot to make me care!
First, I have no problem with built in Cooperative play, as an option. I think it's a perfect feature but I do have an issue with it when it affects my solo-play's achievement record. Choosing to play solo and not being able to complete the game with an 100% achievement record is just as annoying as paying for a game that doesn't really work in the first place. (i.e. Star Wars: TFU2 for PC and it's cut-scene perma-crash halfway through the game that's never getting patched.)
Having artifacts and collectibles locked away and inaccesible to a solo player who made the decision to play the 'single player version' of the game, from the onset, makes me want to write this public review instead of finding someone to group with.
"...Just move the missing collectibles back into the solo game or de-list them from the overall game achievements. Consider solo and co-op 2 different and distinct games all together, simple."
Lastly, Ellie. What can I say. But, for one of the main reasons to push on through to the end and try to save the day, in Dead Space 2, with that rare but endearing Kyle Kataarn/Jan Ord (SW: Jedi Knight 2 - Jedi Outcast) relationship being hollowed out from the start of Dead Space 3. She immediately lost her "Peng" factor both in graphical display and story. I just couldn't bring myself to care if she made it out of any particular predicament, in the later chapters through to the end of the game, or not. Honestly, the entire cast didn't strike a single cord. - "They were there, then they were gone. Ah well, shoot and scoot."
All that being said, I still give Dead Space 3 a solid 8.5 out of 10 for my opening comments but wonder if a future Dead Space 4 can make things right for me or kill the franchise, in my eyes. (Customizable suits - mix and match from available list, texture and color choice would be a nice addition for DS-4.)