Wario Ware D.I.Y. has some good and bad but I'll start with the good:
Good: Fun and addicting like the other WarioWare games. Can design your own games and you can share them via WiFi. Shows Nintendo still has respect for it's 8-Bit games by having Super Mario Bros. stamps, musical instruments, and hell, if you name your game "MARIO PAINT" the graphic editors will play badly rendered versions of the three Mario Paint in-game themes.
Bad: Although you can create your own games, you are given very limited tools for doing so. You won't be getting sample importing from the microphone, many colors to choose from, more predefined instruments, no echo effects, or anything that will help you be creative. Nintendo cuts corners and channels creativity yet again so you might as be creating games with Basic.
Ugly: N/A