I just bought it this weekend. I agree that the drums are ridiculously addicting. I too was a bit bored with guitar and bass after playing GH/2/3 but I love the drums.
I'm also a TERRIBLE singer, but I get amusement and fun out of the vocals.
My girlfriend is a fantastic singer, and was able to do all the songs we played on Medium without even trying. She even did Beastie Boys' Sabotage, which is strange to hear with a female voice.
I'm at work now, but I desperately want to go home so I can play it more.
