The first that came to my mind while playing WarioWare D.I.Y. was "It's about freaking time!"
The first sentence may sound like I'm being a idiot and saying that since there are no games here, it makes this game good. That';s not waht I'm saying. The thing is, YOU make the games! Sure, it comes with 90 pre-loaded games, but you don't buy the game for those. Quite frankly, those games suck. What you buy this game for is to make your own wacky microgames and share them with all your friends.
As you play through the game, you'll unlock all sorts of things. You'll unlock different creation tools, even more ways to play the games you've created! And trust me, as time goes on, you'll begin wanting to play this game more and more. IT just keeps giving. At first, you'll say "oh, well this sucks. I don't have this or that". Then, you pop into the game maker, make a quick, short, and fun microgame, export it, and, HOLY CRAP! You have that now. IT just opened up a new level of awesome. And those things keep popping up all over the place, wether its new ways to mix together the different games you've made, wether you can make a record or a comic, as well as a game, or even wether you can listen to, play, and read most of the things in this incredible package. There truly is no end to WarioWare: D.I.Y.
In conclusion, WarioWare is a game that everyone must own, even if you don't like the series. The actual production process of a game is to difficult to go into detail right now, but once you go through the first basic tutorial (you have to, in fact) you can begin to make games in an instant. Anyone can make anything they want, and aynthing they make can be played any way they want. Its an awesome experience that gets even better when you factor in the fact that Nintendo has promised a never-ending stream of downloadable content. Get this game RIGHT NOW.