Very, very good, and still could be better
There are a few key differences between Twilight Princess and Ocarina of Time (the game that TP is so often compared to). First off, Link doesn't have magic or an ocarina in TP, which is a major change in the Zelda formula. TP makes up for this exemption by giving Link more weaponry and moves such as the ball and chain, the dominion rod, back sword slices, flip sword slices, and, my personal favorite, the spinner.
These items do in fact make up for the lack of magic and magic based attacks, but I found myself thinking how much more useful the developers could have made each of the items. For example: the ball and chain, which is a totally badass weapon, is really only used to smash ice and defeat ice enemies. If it could have been used to do something else; say knock down pillars, break cracked walls, smash windows, etc; then I would have been happier. A major disapointment was the spinner puzzles. Although they were pretty good, I was afterward wishing for a gigantic room entirely filled with spinner tracks that put you at 30 mph or so as you went up down, around, and shot you huge distances from track to track to get to the next door. That would have been a SWEET addition to the already outstanding Arbiter's Grounds.
One thing I really did like about the game was the variance of the temples. In Ocarina of Time, the temples have pretty unoriginal names, like the fire temple, water temple, shadow temple, etc. In TP, every one of the temples except for the Forest Temple (that's a given) have fresh names, such as the Goron Mines, the Lakebed Temple, Arbiter's Grounds, City in the Sky, etc. I am very glad they included the Temple of Time in TP; this was something I wanted to play in OoT, but it wasn't part of the game dungeon-wise.
The Legend of Zelda: Twilight Princess is an outstanding game. Just buy it and cure your Zelda fever; it won't get better until you play this game.