Great challenge, fun and over all an awesome game.
The characters in the game are very memorable, even though this is the first in series that I've played. The wit of both Dante and Nero, wither they're speaking to each other or to a boss that one of them will face generally left me smiling a bit, but not making me laugh much. The story line is actually done rather well, even the swapping of characters feels like a good flow.
When you play, you can really tell the bosses apart each of them having their own moves that differentiate them from the other bosses, although you end up facing each boss three times though out a single play of the campaign, they do become harder each time, still providing a challenge. But the reuse of the level design doesn't bother me greatly, I liked it after I beat the game the second time, because then I can run though the levels much faster, getting an S rating all the time on missions, while maintaining an A on red orbs found.
The games rating system for each time you beat a level awards you with Proud Souls, which are used to purchase various skills on both the characters, the skills range from sword combos, to being able to charge up which ever gun your using, making your Devil Trigger last longer, doing some powerful moves(that can be very easily interrupted), and a few skills that will provide a very effective way of dodging on Nero. The souls are refundable, if you test out a skill and don't like it, there's no penalty for refunding the skill. Ratings are based off of S, A, B, C and D in three categories: time, style points, and red orbs; D being the lowest, S being the highest.
As I just stated, you will end up facing each boss three times, twice as Nero and once as Dante. Your first fight using Dante might provide a bit of a challenge, as it does take 11 missions before you start to play him, by that point you will be used to playing Nero with his Devil Bringer arm. You'll grow accustomed to launching an enemy in the air, then using the Devil Bringer to do a special move to the enemy, while still in the air you'll grab an enemy using the Devil Bringer's snatch ability, by locking on to them and hitting the Devil Bringer's button. Then repeating this will generally allow you to avoid being hit, as well as build up your style meter.
Moving on and playing Dante can provide some amount of challenge from the change, but nevertheless the short time that you do play Dante, you have much more freedom with what types of moves that you can pull off, you have four different stances, three different types of swords, and three different types of guns to use. The control scheme to switch between all of these is designed very well, you can easily switch stance, sword and guns without minimal trouble; I did have some trouble switching stances at times, you might have to hold down the button for the stance that you want, at times my stance would change back to the one that I was just in prior to attempting to switch, but at other times the stance would remain in the one that I chose.
I'm void from talking about the graphics, I don't have an HDTV, but from what I've seen, they're good, and have a stable FPS.
Overall, the difficulty might scare some people away, but if you're looking for a challenge with good game play and just a good time over all, pick up Devil May Cry 4.