While Lips certainly might not be the end-all, be-all of karaoke or music games, the microphones are damned nice. For one, they're wireless. They also have a nice weight to them. And, best of all, they light up.
Unfortunately, it doesn't look like you'll ever be able to use them with Guitar Hero World Tour. Activision has confirmed with VG247 that they have no plans to patch their title to work with the peripheral. Boo!
On the other hand, Harmonix has stated publicly that Lips microphone support would be something they'd be patching into Rock Band 2 on the Xbox 360. That was in November. It's March. The Lips microphones still don't work with Rock Band. Boo!