During the Chris and Piers campaign there is a part on the aircraft carrier that you grab keycards and fight regenerators (name?).
My brother was playing as Piers and we split up for a time. While I was exploring a far off room my bro was caught off guard in a corner of another room that was quite far from my position. Regenerator legs and a hand came charging into his room. My brother tried to open fire on the hand, but the boat rocked and knocked Piers off his balance. Right when that happened the hand jumped on him and the legs were closing in. While trying to shake off the hand the legs came in and started spraying acid on him (while still fighting with the hand) and he was hurting quite a bit. I watched the entire event with my peripheral (splitscreen) and it was absolutely terrifying. Luckily I sprinted across the ship and came to his rescue with a shotgun. It was hilarious because he was quite vocal. He's 33 and he was so freaked out by the whole thing.
That moment will remain with me in video game history as being one of the most tense, scary & fun moments and it didn't even happen directly to me. I just happened to see it on his screen.
Moments like that and many other memorable moments really make me wonder why people don't like this game?
If they weren't really fans of 4 and 5 I can understand why they wouldn't like 6. However if they were fans of 4 and 5, but hate 6... than that is strange. I definitely liked it more than 4 and 5 because of the great co-op. It's easily one of the best co-op games I've ever played.