RE5 felt so much better in Co-Op. It's the only way I want to play the game. Amazing experience.
I have played solo as well, and it just doesn't hit the same. And yes, Sheva's AI is really a low point.
One time I had my back turned towards an area where there are some zombies, because I was shooting the ones in front of me. But Sheva was also standing in front of me, and facing me (so she would be able to see if any approached me from behind).
I figured I'd look at her and see if she starts aiming at someone behind me as an indication for if there's danger behind me.
Azombie walks up and grabs me from behind. 0 reaction from Sheva....
Btw, the developers said that they were experimenting with the moment light transiitions from going into a dark room from a sunny area, and vice versa. Perhaps that's part of why it wasn't set in a completely dark area.
It's good that you enjoyed RE6. I sadly did not.
It had some good moments, and Leon's campaign felt more RE than the others. (The way Chris' started felt like Call of Duty)
Being able to play as Ada again was nice.
One thing I didn't enjoy was that there was no storage box any more, forcing me to discard items frequently.
Perhaps more than I did any all other RE combined.
I did play it co-op as well. And we had some fun moments, like when I accidentally ran over my friend with a snow scooter and dragged his body across a bridge.
Just like you, I thought the RE5 trailer looked amazing.
And it's Resident Evil. I didn't bother with any reviews. "Of course I'll like it". So I bought it Day 1.
Since then I no longer blindly trust Capcom with any new Resident Evil game.
Although I did end up liking every mainline RE game that they released since then. But I no longer expect that I automatically will.