One area where Devil May Cry 4 really suffers in comparison to the older entries in the series is in how they handled Dante's section of the game. When Dante becomes the controllable character in mission 12, he begins a trek back through all of the areas that Nero has passed through earlier. As such, the second half of the game is a reprise of the first. Now then, earlier entries in the series used this same trick, and it is a perfectly legitimate way to proceed through a game if done well. However, the Dante section of Devil MAy Cry 4 ended up feeling tacked on because the developers did not change the old areas nearly enough to make the experience of reprising them feel new or interesting.
Returning to old areas is actually a classic element of the Devil May Cry series. In missions 16 through 19 of the first Devil May Cry, Dante goes back through the areas he first went through in missions 1 through 8 (as well as a few others). In Devil May Cry 3, Dante first climbs up to the top of the tower of Temin-ni-Gru, then descends down into its basement, and finally climbs all the way back up to its roof. However, the difference between these two games and Devil May Cry 4 lies in how they handled reprising old areas.
In the original Devil May Cry, it is daytime when Dante first arrives in the old castle. While the castle is completely loaded with demons, it otherwise seems to be a fairly ordinary castle. However, as Dante moves onwards and completes missions, day gives way to night, and by the time Dante returns to the keep that he explored in the first few missions, it is completely dark out. While the change in lighting is enough to make exploring the castle more difficult, the castle itself seems to become possessed by evil after nightfall. Walls lined with suits of armor take the place of doors, the internal structure of the castle seems to have rearranged itself, and certain parts of the castle, such as the cathedral, take on a twisted, biological appearance. The transformation of the castle works very well because it successfully twists what was once familiar and known into something unknown and much more frightening. The game also shakes things up by adding new rooms, new ways of getting around, new enemies, and a brand new, really difficult boss to this section of the game. It is impossible to say anything bad about this execution of the idea of returning to old ground.
In Devil May Cry 3, Dante does most of his backtracking through familiar territory in missions 14 through 17, where he climbs back up to the roof of the tower from its deepest basement. However, the game throws a twist at the player. At the end of mission 13, the entire tower transforms: the tower's height increases significantly, rooms that used to be connected are now on separate floors, some old rooms have collapsed, and new doors and passageways have appeared. As such, climbing back up the tower is not as simple as going though familiar areas backwards; it involves trailblazing completely new paths and getting used to new ways of exploring the tower. While this section of the game plays off of the familiarity of the old areas, it is in practice an entirely new set of areas to explore. To top it all off, the player fights two brand new bosses during this section of the game.
In contrast to what was done in the previous games though, the player does just play through familiar areas backwards after Dante takes over in Devil May Cry 4. While the game does try to mix things up a bit by adding a couple of new elements to the areas, the changes are superficial at best. For example, Fortuna castle has the exact same layout as in Nero's go-through, except that ice walls have appeared to shepherd Dante down a specific, roundabout route. Th only change of note is that a door that had been previously blocked off (but still on the map) is now mysteriously open, revealing a single stairwell. Other areas were not so fortunate. Dante travels through the underground lab in the exact same direction Nero did, fighting more or less the same enemies (in the same rooms), with the single change that he has to deal with a cloud of poisonous gas that is more annoying than interesting. The only area to get a real change in mood is the forest, which is filled with rain and a creepy fog that has rearranged the connections between rooms. However, the forest reverts to its sunny, familiar self as soon as Dante slays the area boss. Heck, even the "lost woods" puzzle is completely unchanged in Dante's go-through, with the exact same clue and solution. The entire thing is compounded by the fact that Dante fights the exact same set of bosses that Nero fought (minus the most interesting ones) in the exact rooms that Nero fought them, with only a single exception. All told, Dante's side of the game completely lacks any interesting twists to keep things novel or interesting.
Devil May Cry 4 might have been a lot better off if it had used some of the same tricks that the previous installments used to make familiar material fresh and interesting. At the very least, it would have been a good idea to have made Nero pass through the areas during the daytime and Dante at nighttime, or vice versa.