Yoshi's Island DS feels like a cheap rehash of the original SNES game.
Yoshi's Island DS also has fewer stages than the original, even though several levels feel as if they were taken straight out of the SNES game and just changed slightly to fit the few gameplay changes.
Yoshi has all the abilities from the classic game. He can for example eat enemies and lay eggs that will follow him (up to six), throw eggs across the screen and flutter in the air a bit with the press of a button. Not much to say here - it worked in the first game, it works here.
The few gameplay changes I mentioned earlier include the addition of more babies with special abilities that you might need to rely on to finish a stage (Baby Peach, Baby DK, Baby Wario and even Baby Bowser, along with the familiar Baby Mario).
You can only switch babies at certain points in a level and sometimes you will have to use a specific baby to collect certain goodies or simply to progress in a stage. For example, Baby DK can grab vines and lets your thrown eggs explode on impact.
Now, this does seem a bit tacked on and might also lead to a lot of unneeded backtracking or frustration when you realize that you're currently traveling with the wrong baby. I preferred the first game, which was a lot simpler, but still way more enjoyable - you just had Baby Mario and explored several fantastic and wacky levels. This game seems to focus a bit too much on the abilities of the babies instead of making the stages generally enjoyable - the same obstacles are thrown at you again and again, so you might get tired of that new game mechanic quickly.
Somehow, the game also manages to have worse graphics than the original SNES game, including sprites that may or may not have been drawn by four-year-olds on a sugar hype. The music is completely unmemorable for the most part. Many of the classic sound effects appear again here and they are probably the least irritating part (if you happen to like constantly looped screams of babies, anyway).
The goal is not only getting to the end of a stage, but also collecting the 30 stars, 20 red coins and 5 flowers (as in the classic game), plus a baby coin (new) hidden in each level in order to unlock extra stages or minigames.
For some inexplicable reason, they also removed the items that were one of the most fun parts of the original game. Those items would grant you for example the ability to see all red coins in a level (normally they look like regular coins until you collect them), freeze enemies, or grant you some extra stars (each time an enemy hits Yoshi, he and the baby get separated, and for each second they are separated you lose one star - extra stars are rather hard to come by, so if you want a perfect level score in Yoshi's Island DS, you'll have to finish most stages pretty much flawlessly).
Now let me ask one perfectly legitimate question: WHY? Why were the items removed altogether? In the original game, they were pretty much the only reason for playing the minigames - here, you can just play the minigames to rack up extra lives, but you'll have like 100 of those anyway once you finish the game. The removal of the items was a very bad choice and just makes the game all the more frustrating.
As said before, some of the stages feel recycled, so do some of the bosses. And yes, this game also has fewer bosses than the original... naturally.
Avoid Yoshi's Island DS and dust off your SNES to play the original and far superior Yoshi's Island, or keep an eye open for the GBA remake (Yoshi's Island: Super Mario Advance 3). But stay away from this one.
Well done, Nintendo. Once again you ruined a great classic game with a crappy cash-in sequel. So... congratulations?