I've been playing Devil May Cry since the first demo for DMC1 on Resident Evil Code Veronica. This has been may favorite franchise for years, so I have some perspective on this game.
The general sentiment of most of the comments are accurate for the most part. The lack of taunt and lock-on is a little annoying, but you get used to it fairly quickly. The combat is fluid. As far as the story, it does tend to take itself a little too seriously, but it was entertaining enough to keep my attention for a couple of playthroughs.
The difficulty and mission ranking are quite disappointing. I was able to SSS rank DMD without much effort at all. Reiterating previous comments, get the demo, it's pretty much indicative of what the overall gameplay is. I'd give 6.5 - 7 out of 10.