The first Digimon game released by Bandai for the Nintendo DS. Guess Bandai also took steps to monopoly the marketing for NDS.
Unlike the game title implies, Digimon World DS is rather different from Digimon World (PS). In fact, both of the game has but only one thing in common - raise digimon. The only things that matters is you do not need to concern about your Digimon life age, care for it's food, bring it to bladder, etcetera. Personally I did not like Digimon World (PS) as I'll need to take care of my Digimon every second, starting from the moment I load my game file. So if you are going for toilet or even answering a phone call for a moment, make sure you Pause the game to prevent yourself to miss a certain event that may occur to your Digimon.
So in Digimon World DS, it's a contrary of Digimon World (PS). You just need to level up your Digimon, train it or leave it in the Farm, then you're up to go. No need to extra concern like the Sims. Although Digimon World DS include three characters from Digimon Savers (which you'll meet in the beginning quest) such as Touma, it's a different plot. You take part not as a DATS, but as a normal tamer that being 'sucked' into the Digimon World without any Digivice at all. You get it at the moment after you arrived in the Digimon World. I couldn't figure out how on earth is this happening though, to be teleported inside a Digimon World without a Digivice? Anyways, One you're in, you'll be given a certain briefing and then you'll be choosing your first partner. Any partner will do as you can obtain them in the game later.
Unlike Pokemon game, there's no such thing as DigiBall to capture or be friend with a Digimon you met. In fact, you scans them. Once the scanning percentage is over 100%, you can digiconverting them to their physical form by accessing the menu in the DigiFarm. If you had played Digimon World 4 for PS2, the DigiCentral is almost alike with DW4. With portal and such.
Like the other Digimon game, but unlike Pokemon game, level doesn't matter. The only things that matter is the Stats. Just as Digimon World 2 (PS), there's a level cap for each digimon. In order to maximize the level cap (aptitude is the term in the game), you'll need to keep on Digivolve and De-generate your Digimon until it satisfied you. For a perfectionist, level 99 is the max and the max value for each stats is 999. The level and stats cap is rather moderate and acceptable compared to DW2 which the level cap is 999 and the max stats is 9999. It's just insane for one to raise such Digimon without any cheat codes.
If you want to complete the quest, you'll probably feel bored after doing the first few quest. For every quest, it'll whether required you to go looking for a certain items in a dungeon or just talking to someone in the DigiCentral to obtain the items. The same process go through for most of the quest, or should I say, EVERY QUEST. So why bother to do the quest anyways? Well, you'll earn Tamer Points for each quest. After you had reached a certain Tamer Points, you can talk to a professor in the DigiCentral and you'll be given some items.
There's no need to level up your Digimon to the maximum level, plan your Digimon Team for battle or any other things like you did with Pokemon games. In Digimon World DS, you can only do a Egg Matching event with other friends via WFC. For digimon battling, you can only access the wireless connection features, with other friends near you. So you'll mostly spent the time with your hardly raise Digimon for nothing aside from completing the Digimon Gallery.
For the battle scene. You can never see your Digimon sprite during battle. In fact, you can only see your enemy sprite. The good thing is the illustration for each Digimon is great and the size is rather logic. You start the battle with only 3 Digimon. If all of your 3 Digimon had been KO'ed, then you'll have the option to exchange them with another 3 of your relief Digimon (if available). All the enemy HP will never exceed 999 except for bosses. So just as I mentioned above, there's no need to max out your Digimon stats. You'll end the battle in merely 3-5 seconds when you're progressing in the later of the game. The enjoyment and excitement is not as fun as Pokemon.
In conclusion, Digimon World DS is worth playing when the game is released last year. If you had decided to go to a local store for this game, don't. Just wait for another dual release of the game - Digimon World: Moonlight and Digimon World: Moonlight (both name in Japanese) as the next installment include a wide range of improvement. The US release date is due to confirmation and will probably be released in 2007 September. Just stick to Pokemon Diamond or Pearl until then.