I'm in the same boat as you. Really loved RE4, quite liked RE5 and disliked both demos of RE6. The full game was a huge disappointment. I beat it, sure, and it isn't completely awful, but it is easily the worst RE game in years.
Every single flaw from the demos is present in the full game. In fact the full game has way more problems (like repeating missions, or inconsistent save system). I can't say there was only bad stuff, but the only way to enjoy it is to adapt to the terrible game design of this game and constant bugs. I lost count of all the melee attacks, or counters that missed the enemy, when they really shouldn't have. Things like this almost never happened in RE5. I remember only three melees that missed in RE5 (and 2 of them were through an obstacle, so it is understandable) and played more than 150 hours of it.
Well I didn't like the demo much, didn't really give me a good enough feel for the game I thought. On a whim, I preordered the game a few days before and don't regret it myself. Logged about 100 hours so far, even having trouble playing Halo 4 (which I do like) because I want to jump back for more mercs.
Gamertag: Pickle Swift 3DS friend code: 4339-2579-4895
I personally have mixed feelings about this game. It would be a lot better if Capcom if they would have appealed to their fans and not their wallet. They went over the top with QTE's that you will die. A LOT, it really ruins the game when your doing the same part 3 or 4 times (cut scenes included), because they decide to add a QTE with little warning or a lack of promting as to what you should be doing til its to late. If your a die hard fan, maybe buy it once the price drops. I would recommend just renting it or borrowing it and getting your fill. Its definitely not what you would hope it would be.