We went to Kbox on a Monday for their 50% deal. The guy that helped us out seem kind of scared of us/nervous, but very friendly.
The system they use is easy enough to use, but there is something helpful about being able to leaf through a book of songs to be inspired. They were missing some classic songs- no SHOOP? Also, a lot of times the lyrics weren't in sync with the music so you'd have to concentrate pretty seriously not to f*ck up the song.
I like that they have tambourines but I wish they had party lights. It can be a little boring to do karaoke with a regular overhead light on. There is also a window through the door so people can stare at you... didn't really like that.
I've been to a ton of karaoke places and while this place had a TON of value for Mondays and Tuesdays, I wasn't overly impressed and wouldn't run back.