Every comment I've heard about the game from other people has been one of the following things:

"Dante is no longer cool in DMC2. He barely speaks, and none of his lines are badass or interesting at all. He's dull and boring."

"The levels are too fucking long and quite poorly designed."

"The weapons are lame and generic. Alastor, Ifrit and Sparda do not make the transition to the second game. Instead, they have been replaced with boring, predictable swords with names like 'Vendetta'."

"The long-range weapons are dull too. No cool demonic weapons like the Needle Gun or the badass Nightmare Beta. Just a couple of machine guns, a rocket launcher and some handguns."

"None of Dante's new badass moves are useful in any way. Running up walls was placed into the game solely so you could say "ooh, cool", shooting at multiple targets is basically just in there for flair, and the juggling system has been made into a repetitive bore."

Those are the most prominent complaints that I've heard about the game. Apparently it looks and sounds great, but the gameplay is nothing short of mediocre.