Awesome game, easily one of the best on the DS.
The gameplay is very unique, in the way that you have to direct Link with a stylus rather than an analogue stick or buttons. This takes a little bit of getting used to, because not only Link is moved this way - everything in this game has to be done by stylus. Combat is done by stylus. However, a few of the puzzles require mic usage, something very unique. Many of the dungeons have clever puzzles, fun battles, and amazing bosses. Also, sailing the seas is also a fun thing to do, and also gains access to many side quests, many of which are quite funny - helping a sailor who fell in love with a mermaid, etc.
The graphics and sound are some of the best on the DS. The graphics are very good, but in some cutscenes, where xlose ups are used, it sometimes feels too pixelated. But that's understandable - this is a DS game, after all. The game not only boasts amazing character models, but good textures and special effects. You'll definately be sucked in when the calming music kicks in as you sail in the S.S Linebeck, watching the tides roll and the seagulls flying overhead.
Phantom Hourglass is an amazing game, boasting terrific gameplay (albeit a bit easy), plenty of dungeons, superb graphics, all which will keep you ocupied for the 20 or so hours of gameplay packed into this terrific cartridge.