[Pay no heed to this play time. Trust me, I've played a lot more than what's shown.]
While not quite reaching the perfection of DMC3, DMC4 still stands as one of the best of the genre. The tight gameplay, great music and unforgettable characters make this game very worthwhile to pick up if you're a fan of the genre.
First off, this game looks gorgeous. The environments are very beautiful, and the setpieces are marvelous. The characters themselves look very good, even though they don't actually look too realistic. For a 6 year old game, the visuals definitely still hold up to this date. Also, this game can run perfectly even on mid-range rigs (my 820m could run it at a smooth 60fps all the way, although at 720p).
The gameplay is what really makes this game shine. The controls are very tight, whether you're playing on a gamepad or with a keyboard (gamepad is infinitely better, but keyboard is still great if you're used to it. If you're not, it won't take long to get a grip on the controls, trust me). You never really feel like deaths happen on the game's end, and not on yours.
While hacking your way through the smaller enemies is great, the bosses is where this game is at its best. Recognising their patterns and acting accordingly is what it's all about, and it feels seriously good if you manage to pull it off. The gameplay distinction between Nero and Dante is also very good. Both have upsides and downsides, and I can't really choose favourites. Dante is so fun because of his different weapons and styles, and Nero is so much fun because of his Devil Bringer, and the many uses it brings with it. Who you'll like more is all up to you to decide.
The only real downside is how Dante's side of the story is a literal backtrack of Nero's story, down to fighting the exact same bosses. This bogs it down quite a bit, as there is a lot of missed potential here. However, fighting these bosses again with a different playstyle does feel fun and refreshing, so that makes up for it a bit.
All in all, this game is seriously great. Learning it may be easy and quick, but mastering it to get to the higher difficulties is very difficult and very fun. Pick it up if you like these games. You won't regret it. At all.