Game & Wario is kind of like Nintendo Land in reverse. Where Nintendo Land takes the gameplay concepts of various Nintendo franchises and condenses them all into a Mii-sized caricature, Game & Wario takes the micro-game sensibility of the WarioWare series and tacks it onto a variety of modernized Game & Watch-style arcade games. It's a fusion of one of Nintendo's oldest, arguably most simple game series and one of its most strange, surrealist franchises. It's a new combination of old ingredients, not unlike the Wii U itself.
In fact, some of the games in Game & Wario were at one point planned to be pre-installed on every Wii U console, like the SpotPass games on the 3DS. Many of them were among the first "experiences" available for play during the Wii U's initial E3 unveiling in 2011. The Wii U is the reason these games exist, but is there reason enough for you to buy them?