This game is iconic. There is so much that's good about this game. It has some of the best enemy design in the series, and the combat, while a little thin compared to other games in the series, still feels great.
As much good there is in the game though, it has its list of problems as well. Boss battles are weak (excluding Nero Angelo), platforming is bad, and the Kamiya gimmick levels. The final boss is egregious, especially the shoot 'em up section at the beginning. The underwater sections control just as bad as the first phase of Mundus. Platforming, while not common, feels horrible and is unnecessarily hard. Most bosses aren't terrible, but they don't stand out necessarily. Phantom is cool, Griffon 1 and 3 are fine. Nightmare 1 and 2 weren't as horrible as I remember. That being said Griffon 2, and Nightmare 3 are some of the worst boss battles I've played in a game in recent memory.
Despite the shortcomings of this game, it is incredibly important to the DMC series, and character action games as a whole. Although I can see why some people would not finish or skip this game, this game has too much good and is too important to skip.