I vividly remember getting this game for my birthday the year it came out. And despite the fact that I had a house full of my friends over for a party, and this was a single player game, it was all I did for the rest of the day. No regrets.
The first thing that stands out about this game are the graphics. It's simply gorgeous. It was released less than a year before the Nintendo 64 launch, and the advancement Nintendo made between the original Super Mario World that debuted alongside the SNES and this game are undeniable. Clearly, the powers that be had a firm handle on what the Super Nintendo was capable of at this point. I consider this game to be the SNES's swan song. It's a hell of a way to go out.
Everyone had fallen in love with Yoshi after his appearance in Super Mario World a few years earlier, and we were excited for the opportunity to play as him some more. It took one game (if you don't count spinoff appearances and the awful Super Scope game) for the dinosaur/sacrificial lamb to leap into a starring role. It took poor Luigi like 20 years to do that! (Again, no spinoffs. Looking at YOU, Mario Is Missing.....)
This game featured some new gameplay mechanics, like launching eggs and the debut of Yoshi's "flutter" jump. The levels are deep and lengthy, and I *think* this was the first "Mario" game to feature collectibles in each level that you had to seek out if you wanted to 100% the game. And 100%ing this game was hard. I haven't done it to this day, although it's something I intend to do at some point. It gave you a ton of bang for your buck, and while it isn't really a sequel to the original Super Mario World per say, it lives up to the name sake from a quality perspective.
I'd be curious to know how it would've sold it they had simply called it "Yoshi's Island", without slapping Super Mario World 2 on the cover. I have to assume it would have hurt sales somewhat, especially after Yoshi's Safari was such a disappointment a couple years prior. And without the success of this game, Yoshi might not be as big of character in the Nintendo universe as he is today. People forget that Yoshi didn't appear as a "power up" in a Mario game again until Super Mario Galaxy 2 15 years later.
It doesn't really matter in the end, I suppose. Yoshi is awesome, and so is this game. My buddy Kyle and I had a great time explaining why on this week's podcast. Enjoy.