From a UX perspective, having an interstitial like that can turn off many visitors, especially if it's coming off a search result. They're expecting to get to an article about whatever they just searched, and instead they see a thought of the day plus an ad. While it generates revenue for the domain, it can have a longer term effect of diminishing return or regular visitors.
There was a great article here a couple years ago, identifying customer satisfaction as a primary SEO factor. http://moz.com/blog/seo-satisfaction