We have to admit, we're new to the Devil May Cry franchise, so we can't really compare what we played in the demo to the previous titles. We also have to keep in mind that this is a demo, and they actually have a statement when you fire it up reminding you of the fact, and that there may be issues/bugs with it.
With all that in mind, here's our initial impressions. The game looks really nice, and plays pretty smooth. The environments actually look incredible. The demo contains a couple different areas, including an outdoor landscape complete with snow and blowing wind (VERY impressive), an indoor/chapel area, and an outdoor/ghost-town type area (where you get to fight the hot-headed Berial).
The camera got a little crazy, especially when transitioning from one area to another, or going up flights of stairs, etc.
The best part of the demo is fighting Berial, mostly because he looks incredible. A cross between a centaur and the Balrog from LOTR.
While the demo was a little rough around the edges, and there really wasn't much in the way of good sound effects, or music, Devil May Cry 4 looks like it has a lot of promise. With a little spit, and some extra polish, it may just end up in our library of games.