You can play the battle mode with your friends locally or with people online. For local play, you can pass around a single system or use the DS download feature to link two systems together using just the one cartridge. Lag isn't a problem with online matches, since players alternate turns. However, unless you hit up your buddies and favorite message boards to exchange friend codes, you're going to have a difficult time finding people to compete against online. As of the writing of this review, it seemed there was hardly enough people logged in for random matchmaking to be fruitful.
The dictionary is full of esoteric words like 'loofah' and 'querl.'
Bear in mind, too, that you won't be blown away by the presentation. The frog pond and temple backdrops are static apart from the occasional water droplet. All of the letter tiles are basically just Scrabble pieces, and the only action you'll ever witness is when the letters fly off the screen. At least the letter tiles are easy to read, and the Asian-themed music is pleasant without ever becoming a distraction.
As for the miscellaneous aspects, the game's dictionary recognizes some pretty obscure words, while the touch-screen controls make it easy to pick letters and tap the undo button. Selecting letters by tapping them is much easier than using cell phone keys. The DS game also doesn't suffer from the input lag that many of the cell phone versions do. Another feature exclusive to the DS rendition is the inclusion of an awards tracker, which gives you butterfly medals for achieving various milestones (spell a word worth 100 points, spell a nine-letter word, and so on). It won't be a big deal for most people, but it's a nice motivational feature nonetheless.
All in all, if you're a vocabulary snob and proud of it, you'll probably enjoy WordJong for the Nintendo DS. The basic premise is highly addictive, each mode offers a different take on the concept, and the battle mode offers the competitive edge that previous incarnations were missing.