Crisp, new graphics and exciting gameplay. More of the same for some, but a solid game nonetheless.
One first notable aspect of the game (at least to me) was that it was relatively easier and shorter in duration than the previous installment, so that alone might convince a more "laid-back" gamer who'd prefer an easier and simpler alternative. Luckily, however, the game still manages to maintain the charm and quality the series has always had, as well as the creative and zany boss battles. I also find that the music is very well composed and fits perfectly the often fast, hyperactive, and intense moments within the game.
However, if you're looking for a different storyline than that of the first, you're out of luck, as there is no significant difference between the two (typical "Bowser kidnaps Peach" cliche), except for the setup of the final boss. I would certainly recommend this title to those who are new to the series, as you certainly won't be missing out on anything plot-wise.
That aside, I highly appreciate how the controls have remained the same and haven't made any faulty "improvements", which game sequels tend to do often, hindering the gaming experience. And on another note, I also like how Luigi is introduced much earlier than that of the first game, giving space for more variety. (Though I find that Luigi skids a bit at times.)
Then, of course, there's the new addition of Yoshis, which I'm surprised the original didn't already introduce. Regardless, I find that this is an excellent feature and adds for more (once again) variety. Yoshi can basically eat his way through things and float to heights that Mario couldn't normally reach.
Overall, I'd say that it's a game worth purchasing and a great addition to your collection. Though it might be more of the same for some, I do guarantee it is still a fun game.