Of course the game was flawed. That's probably why Ninja Theory went back to fix the main problems with the actual game in the Definitive Edition. That's more than Capcom or anyone else does with marginally-playable games that they make, let alone horrible, glitch-filled ones. But was it horrible? Not in the slightest...at least, from a gameplay perspective. How bad or good the story was is discussion left to personal taste. You can either compare it to the story of the old games, or take it on its own merits.
On its own merits, the story is decent. The threat is decent, but the premise is kind of silly once you wrap your head around the hamfisted social satire and pokes at consumerism. But it's the dialogue and the central characters that make DmC the slightest bit interesting. The mannerisms and exchanges between characters make the cutscenes worth watching, and Dante's development was executed competently, but not perfectly.
In comparison with the old games, well...the game's plot might as well be a work of Tennyson. I'd call the plots, dialogue, and characters of the old games products of their time, but DMC4 (despite having marginally-better writing than the narrative train-wreck that was DMC3) was released in 2008, while DMC3 was released in 2005. Even for entries released that recently, the writing for both games have aged more like milk than a fine wine.
And no one brandish that BS, self-assured "oh-the-writers-weren't-taking-the-story-seriously" argument that I see plaguing every forum and YouTube comment section. If DMC was never putting any focus on the story, then Capcom wouldn't dish out money on motion-capture, choreography, and consultation with American script-writers to produce an hour's worth of cutscenes for every game, let alone take the time to make a story-driven anime.
