I actually thought the demo was quite riveting. It was only early stuff, but so far I'm impressed. Sure, the story is only half-interesting, it has a cheezy hollywood style to it, the voice acting flat out sucks, the difficulty feels a tad low for a Devil May Cry game, the demon pull mechanic confused the heck outta me, and the platforming controls kinda suck, but the core combat was fun - not as fun as DMC usually is, but better than Ninja Theory has ever done before. It feels like a Heavenly Sword that doesn't suck, for instance, with the way you switch weapons with the trigger. The boss battle on show was also cleverly designed. At the very least, they know how to make this game intense, while also throwing in enough downtime to explore your surroundings, which is quite rewarding.
I honestly don't expect an unrelated party to ever really come close to Devil May Cry 3 and 4, but I think this is as close to them as I could possibly ask, assuming the rest of the game can hold this level of quality. That said, I won't be buying it day one, but that's more because of money issues than anything else. I may pick it up next year, though. And I look forward to it.