I sort of blitzed through the fourth campaign because of Dishonored, but I am interested in going back and playing through all 20 chapters on different difficulties with different characters. This is a good game. I understand where the hate comes from, but, all flaws considered, I've played far worse than RE6 this year.
When you're fighting, this RE is the best RE. It's really fun to play, and its mechanics are great provided you don't bother with cover and actually know what you're doing. Some stuff is kinda quirky, but you can learn to work with those quirks so that they no longer are a problem. Other stuff is a little rough around the edges, too, but that can always be refined in the future.
When you're not fighting is where RE6 stumbles. There's so much variety, but a lot of it is hit-or-miss. Some sections last too long (boss fights in particular don't seem properly tuned for single player) or are really annoying and not particularly fun. Chapters are often about two to three times far too long than they need to be, as well. Since we are expected to replay this content, it needs to be less of a pain to go through repeatedly.
As I said a day or so ago, I was taking breaks from RE6 with RE4 (just messing around with the HD version and random save files in the PS2 version). I was never the biggest fan of RE4, but I respect it and adore what it does well. After playing both in tandem, it's clear to me that each has shortcomings. My wish for RE7 is a return to seamless, atmospheric, relatively quiet, well-paced adventure with "variety" (QTEs and alternative sequences) kept to a minimum and very little loading (basically, the best aspects of RE4) but with the combat (character capability and enemy diversity) that RE6 has (which is what I feel is its strongest asset).
Things like Agent Hunt, Mercs, and Raid Mode (which isn't in this, sadly) are all wonderful extras, and they're even more important if we're forced to deal with bloated campaign content that's not always particularly fun to return to. Mercs and Raid should be really fleshed out (balanced scoring, skills, plenty of maps/levels, etc.) for people who just want to have fun without the padding and interruptions (Mercenaries 3D comes to mind). The way Raid handled things was also pretty good for a "campaign alternative"--many levels were adapted straight from story mode content, and some even had their own objectives beyond simply killing everything in your way. If Capcom insists on kitchen sink design meant to appeal to everyone, they may as well go all the way with these modes, too.
I think the backlash for this game is a good thing but only if Capcom pays attention to it within reason. Earlier RE games will not disappear, so there is no need to retread anything out of fear of losing an audience. I want legitimate advancements with each major iteration, and, for all its flaws, I'd consider RE6 a pretty acceptable evolution. Things definitely could've been handled better, yes--it feels like every last idea was thrown into the game with reckless abandon. If I'm going to revisit a game repeatedly, however, quality is far more important than quantity. Also, Capcom should strive to explain game mechanics and objectives/goals a bit better the next time around. Not everyone is patient, forgiving, and willing to learn from their mistakes, especially when other questionable content in the game is already rubbing them the wrong way.