DmC really wasn't a bad game. Kind of like with a few other sequels from these past few years, it would be a great game if it wasn't a Devil May Cry game, essentially. Then again, I've played Devil May Cry 1 - 3 and some of 4, and I have to say, I don't get why people pine so badly for sequels in that vain. Maybe it's because I didn't play the games when they were brand spanking new, and rather, the first three on a PS3 via the HD collection, but, I mean, they were fun. They just weren't that fun. And if I'm not mistaken, Devil May Cry 4 wasn't really reviewed badly, but was rather obscure outside of fans of the series, which is probably why the redesign happened. They figured the Devil May Cry ship had sailed and were trying to appeal to a broader audience.
If you look at Metacritic, especially at the user reviews section, it is primarily butthurt fans that are basically saying "this isn't a sequel to a series with kind of archaic mechanics and progression methods". The user reviews are brought down by an almost equal number of negative reviews to the positive ones that are likely mostly from people that haven't even played the game (since you don't have to actually leave a review when you rate). DmC was certainly unfairly attacked because it dared to reimagine a series that didn't really have anywhere else to go, refusing to try to remaster mechanics and level design that didn't really click with modern game design. This seems even more likely when you see that all these angry people apparently didn't even bother to rate Devil May Cry 4, with the number of ratings for DmC dwarfing Devil May Cry 4 in comparison.
That isn't to say that DmC didn't have its share of issues, but it certainly deserved to sell better than it did. Unfortunately, I wasn't able to dig up accurate sales numbers, as the PC sales numbers weren't logged when I searched around, but between the PS3 and 360, it still sold over a million copies, so I'm sure they at least recouped their development costs. The only reason it didn't sell more was because the original fan base basically abandoned the game and refused to give it a shot, meaning that most of those 1+ million copies were probably from people that hadn't played Devil May Cry before.
Remember all, older is not simply better. The older Devil May Cry games feel like old games now. They have aged pretty badly, and the only reason you wouldn't think that is if you were a fan of the series to begin with. It's kind of like when people shit on the newer RE games because they aren't RE 1 - 3. As fun as RE 1 - 3 were before, and as fun as they may still be for those who experienced them 15 years ago, they are still clunky as shit and have aged like a turd, so newer games in the same vain would sell like shit, which is why RE4 happened, starting a transition (one that I would argue is still incomplete).
Honestly, Capcom may fuck up, but I give them kudos for not being content with just leaving everything as is, spinning out lackluster sequel after lackluster sequel just because people are so stuck in the past on feelings of nostalgia. With that said, I will still shit on them for whoring Street Fighter.