I wouldn't be surprised if in half an hour to an hour a lot of that information is annotated for you.
It's hard to see the power of Rap Genius unless you use it, but once you do, you realize it's very much a new protocol in the same vein that pg called Twitter a new protocol in 2009. What's special is that a company owns that protocol, and you don't feel like it's owned by someone else.
They have to grow as fast as they can into everything because in just one cycle they can easily retreat and end up as just another features company.
Most twitter users don't tweet, they just follow. Getting the big users on board and figuring out they everyday people don't need to tweet was one of the big epiphanies.
If you look at the google trends, they were basically stagnant until 2009 when they made that realization and focused on activating users by getting them to follow a certain number of consistent tweeters.
With consumer stuff, nothing is ever cemented, but I can assure you that RG is doing quite well wrt to growing that community.
You can see that Twitter survived off blog hype and early adopters for 2 years.