I do love the game though, and love the dark art style that it has, only thing I´d change is the difficulty, and yeah, what Virtua said about the items, a couple of items are really silly :x.
As for the most difficult of 3D Zeldas I´d probably go for Majoras Mask xD Altough I beat it when I was a lot younger, so maybe if I play it now it´ll be a lot easier, who knows :x... Or maybe Ocarina Of Time Master Quest...
I honestly had a lot of trouble with some of Twilight Princess' dungeons. Especially that Sky Temple place. I didn't have any issues with Skyward Sword...but that might just be because I've kind of figured out most of Zelda's tricks at this point lol.
Fi, Navi, Midna, Tatle, etc
It takes a while to actually get into the dungeons, especially in the beginning. There's a certain mechanic you need to do in order to access the world as Link proper, and it felt a bit repetitive and annoying, but the dungeons (save one of the later ones, I shan't name it) are fairly nice, if on the easy side.
The art style really bothered me. While it fits with the darker story, the art was very bland and sour. I was watching a friend of mine play in one of the temples, and the most vibrant and appealing thing on the screen was Link's shield.
Everything else was brown. Or the earthy green of link's outfit.
Mind it was an earthy temple, so the coloring makes sense, but even the spirit temple in OOC had some vibrancy.
In terms of its place among other recent(ish) console Zelda titles? In my book, it's dead last out of Windwaker, Ocarina of Time, Majora's Mask, and Skyward Sword. Twilight Princess, as I played it on the Wii, felt more like a way to test the capabilities of the WiiMote, rather than a way to expand the Zelda universe. It didn't really add anything to the series.