I've played Dynasty Warriors 2 and 3, not 4 yet, sadly.

The games are fun enough, and it's got a nice variety of characters (Zhuge Liang > All. Clearly), and I quite like the music on it, which fits in with the mood of the battles rather well, I think.

The real problem with the game is that it can get horribly repetitive with the same "slash slash. You die. Slash slash. die" action over and over again. Still rather fun though.