5 was mundane, repetitive, and weird. The atmosphere didn't feel tense at all mostly due to having an AI partner and having the setting during the day for a large portion of the game. Having an AI partner meant more enemies. Coming from 4, there wasn't much new that was actually positive or a good idea. Chris was way too buff. Villains had no real reason to being villains. The only good thing to come out of 5 is some expansion to the lore by dealing with Wesker, but we could have done without 5 and it would have been for the better.
6 was a nightmare of indecision. Way too much action and way too many ridiculous set pieces. Capcom tried pleasing everyone by doing "classic" style with Leon, clearly scarier, in the dark, slower paced, actual zombies, etc. Still wasn't like the classics. Then Chris with his straight up Call of Duty style story. Jake with the new monster/nemesis type scenario, and Ada with the secret ops style. None if it performed well in what it was trying to do. Too many useless mechanics like the stamina bar, herb to pill conversion, weird melee combat, overuse of quicktime and button prompts, co-op partner mechanics, etc. I have a bias towards Leon, so I enjoyed his story the most, but it was riddled with way too much ridiculous **** that is way over the top. I don't have a problem with action, but I'm going to keep repeating myself when I say that over the shoulder gameplay is not the issue that plagues Resident Evil and it is possible to make a tense and scary game, much like Visceral Games did with Dead Space.
I have a fairly limited experience with Outbreak. I only had the first game on PS2 and I was about 13 when I played it the most. From my recollection, it was very hard to the point of impossibility. The difficulty was mainly due to limited items like health and weapons. Inventory space was also terrible which was counteracted by the ability to share items, but as far as I recall, the AI wasn't the smartest around. The infection timer was also a pain in the ass and a cheap way to increase re-playability on an already hard game. I only ever recall finishing the bar scenario, the Hospital and Mansion ones I never got too far into. Perhaps it would have been a great game online, but I never got the internet working with my PS2. As far as atmosphere, the game nailed it 110%. It really did feel like a struggle to survive, but just too damn hard. To me it felt like a wasted opportunity. It wasn't TERRIBLE, but a squandered potential.