The Majora's Mask comparison is more than justified. The first ten minutes of the game basically lay out the fact that Phantom Hourglass starts off basically where Wind Waker ends. The look is the same, you're still boating around from island to island. The core gameplay is the same. But it's a MUCH different game overall. You all know that Link's Awakening is a sequel to Link to the Past, right? The gameplay differences are nary any different. It's still top-down, you still get one item on the B button, there are still fetch quests, and there are still 8 dungeons.
Even Wind Waker is a sequel to Ocarina of Time, which is references CONSTANTLY throughout the story. And, in fact, the gameplay is exactly the same. It's a little easier, and the focus is different, but the connections are omnipresent, and the gameplay is basically the same.
Phantom is a sequel to the Wind Waker, but the Wind Waker's influences are only aethetic. This really disappointed me. I'M SORRY. The story failed to sweep me up like it did in Wind Waker (and Ocarina, and Link to the Past, and even Twilight Princess), the gameplay, like GP says, is hampered by the fact that your stylus is blocking part of the screen, and must I say it again? The Temple of the Ocean King sucks!
Look, when you compare this to the GREAT Zelda games of the past--Ocarina, Link to the Past, Link's Awakening, Wind Waker, and for some of you, Twilight Princess, Phantom just does not compare.