I have finished the game (main storyline along with numerous side quests etc).  It's a good game, but I'm hesitant to say a it's a great game.

Pluses:

• Making Zelda the playable character has allowed the designers to create a different gameplay while still still making a game which is obviously part of the series.
• The art style is fun & cute and really emphasizes you're playing a game.
• The echo mechanic often means there are multiple ways to solve a puzzle or achieve a goal.  It definitely scratches the creative itch and gives a sense of accomplishment when you come up with a new way to use an echo or use echos together.
• Early in the game I was thinking "I wish I could talk to the cats" - and that wish came true!

Minuses:

• Echo selection (especially using the simple in-game pick list) is tedious.  I typically left it on "Most Recently Used" as I found I'd be reusing the same echoes in a given region.  But towards the end of the same I spent just as much time using the main (type sorted) grid.
• Several of the boss enemies needed very specific techniques to defeat - and the game didn't seem to provide any hints.  So I found I had to check a walkthrough a few times.
• In addition, there are a few puzzles & enemies where there seemed to be only one solution - which is kinda the antithesis of the spirit of the game.
• The weird tilt-shift blurring at the edges of the screen!

Other:

• Very early in the game you learn how to go up walls - which means you're no longer limited to paths etc.  I'm sure this created huge challenges from a story and dungeon design perspective.
• Because of the straight-on overhead perspective entrances were almost always in the north face of walls or on the ground.