The artificial intelligence (AI) of enemies in Twilight Princess is more advanced than that of enemies in The Wind Waker. Enemies react to defeated companions and to arrows or slingshot pellets that pass by. The AI can also detect Link from a longer distance than in previous games.
They should appeal on some level to those who are fond of the series; however, I’d like them to have entirely fresh surprises, too! Yet I’d also like them to have thrills that echo the past, so they have feelings like “I know this! I can do it!” and “Holy cow! This is how you brought it back for Twilight Princess? Awesome!”
I also focus on creating enemies that perfectly fit the environments. And here’s where the idea of what Twilight Princess’s style really is comes in. Some have misunderstood it as “photorealistic Zelda,” but it’s actually “realistic Zelda.” And by realism, we mean that it is really important that players get a very realistic sense that they’re deep in the game, which involves more effects than mere photorealism. This is more complicated than you might think when it comes to monster design. I try to be very careful to create monsters that enhance the sense and pacing of adventure in each phase of the game. For example, let’s say you’ve just beaten a small enemy. Later on, you should possibly meet with the same kind of foe but larger. If you continue to beat those, you should eventually meet up with a massive version of the creatures. This kind of progression helps create a storylike feeling, even when simply battling through levels.
All of these quotes tell me one thing: that TP's enemies were planned to be dangerous, yet still beatable. However, the foes were NOT dangerous in any capacity - and it wasn't because they dealt too much damage (although the damage:health ratio was abysmal, but more on that later). The thing is that the enemies a) do not attack very often and b) have only one or two methods of attack. See that Bulbin in the distance? He has a club, right? Well all he'll do is whack at you with it. He won't do a hard bash to knock you off guard. He won't jump around. He won't even defend himself*, just sit there and shuffle while waiting for his "turn" to attack in his normal abnormal manner. So what I'd fix with ZeldaTP is make the foes attack more often, have more attacks to keep things fresh, and generally be more dangerous/deal more damage.
*Do NOT make it like SS where all the enemies do is defend themselves.
Sources: http://www.zelda.com/universe/game/twilightprincess/inside10.jsp
http://en.wikipedia.org/wiki/The_Legend_of_Zelda:_Twilight_Princess