I agree. People that have followed Mixergy know the content is worthy. However, I can certainly see how someone finding it for the first time might be turned off.

My main constructive criticism would be this:

Don't make people spam their Twitter followers just to view the premium samples.

a) It annoys people that don't use Twitter (yes, we exist) b) It makes me have to have a relationship with you before I've even evaluated your content.

In my mind, it's more effective to allow people to sample your premium content with the least amount of resistance.

Keep the list building separate from the sample content. You can always find something to give away specifically for the list subscribers.