Yoshi needs to get a restraining order against Artoon.
I should learn not to hope.
At first, the game feels like a welcome trip down memory lane, as it plays much like the original: The same hopping, bopping, baddie-eating, egg-throwing action, the oversized boss-battles, the same cutesy coloring book environments that fit the game so well. It's nice to see that Artoon didn't try to fix what wasn't broke as far as these were concerned.
However, the DS should be able to do special effects better than the SNES, shouldn't it? Well, it's not happening here. There's no polygonal stuff (like the tumbler platforms in the original's castles), Kamek's boss spells lack any special effects... On the other hand, Yoshi's transformation sequence into vehicles in some levels actually looks better, and is conveniently brief compared to in the original. The audio suffers even more than the special effects. The sound effects are distorted and the music is weak and not memorable at all. There's seriously no excuse for this.
The game's big draw is the baby-switching system. There are 5 baby sidekicks Yoshi can carry around, each giving Yoshi different abilities. Mario lets Yoshi run faster and can hit special M blocks, while Peach has a parasol to catch strong winds and reach new heights. DK can climb and swing on vines, and Wario has a magnet to attract coins and other metal objects. Bowser (it's not a spoiler, it's on the box art) can breathe fire, which has unlimited ammo, unlike the eggs. Because of the specificity of these skills, though, it becomes obvious who you need and what you need to do during the levels. Heavy wind? Get Peach. Metal blocks in the way? Get Wario. Part of the problem with the level designs is that they start to become the same baby-related puzzles over and over again.
The other problem is that much of the rest of the levels consist of exercises in frustration. It's only natural that a game should become more difficult as you get closer to the end, but this game overdoes it. There are scrolling levels that give you few opportunities to get eggs and many situations where you need them, swarms of enemies, moving platforms over bottomless pits that go through gauntlets of fire or spike hazards, and other hair-tearing obstacles. And it's even worse if you're trying to get 100% completion for a level, since part of that requires beating it with a full timer, and getting hit causes you to temporarily lose your baby, with the timer counting down until you get them back. Oh, and did I mention that you can't use the babies' unique abilities until you get them back? If you're over a large, windy bottomless pit with Peach, getting hit can all but screw you over.
Artoon tried adding new methods of transportation to add some variety to the levels, such as a new nameless kangaroo partner who is apparently supposed to replace Poochy the dog. The kangaroo just jumps higher than you do, and it only appears in a few bonus rooms filled with coins, so you don't actually need it to progress through levels. Whereas Poochy would provide safe passage over spikes or lava, and was actually useful. The lack of usefulness plus the kangaroo's lame character design just scream "rushed". There's also stilts and a rocket. The stilts aren't bad but still feel unnecessary, and the rocket sequences really could've been pulled off better.
The gameplay takes place on both screens, so the other mostly doesn't go to waste. You can get a better look at items hanging in the sky or look ahead in areas where you move vertically. However, there's a blind spot between the screens where the hinge is, and it's not unusual for items, platforms, or more dangerously, enemies to hide out in this gap. The Touch Screen doesn't get much use – just in menus and bonus mini-games at the end of levels, but I suppose that's a good thing. A platform game like this wouldn't need much, if any, and it's good to see Artoon didn't try to shoehorn in some badly-executed gimmick for it.
After all this negativity, did they do anything right? Well, as mentioned before, the graphics and environments look great, lack of special effects aside. Some of the character sprites have been given a slight improvement over the original, even, most notably Yoshi himself. Yoshi is perfectly controllable, though a few tweaks to the egg-throwing and some baby-specific moves may take a little getting used to. And the giant boss fights are still fun.
I hate to be this negative towards a game, but a DS game can be much better than this, and a sequel to Yoshi's Island should be much better than this. The whole deal is a disappointment for those who played the original, and the lack of effort won't make it worth the price for those that didn't.