[mnicole]

Studies show that it takes less than a second for visitors to determine - based on appearances - whether or not your site will bring them value. The Nielson Norman Group says that in addition to this, you only have ten seconds to provide written-proof of that value:

> the first 10 seconds of the page visit are critical for users' decision to stay or leave. The probability of leaving is very high during these first few seconds because users are extremely skeptical, having suffered countless poorly designed Web pages in the past. People know that most Web pages are useless, and they behave accordingly to avoid wasting more time than absolutely necessary on bad pages.

> To gain several minutes of user attention, you must clearly communicate your value proposition within 10 seconds.

> http://www.nngroup.com/articles/how-long-do-users-stay-on-we...

The author is assuming a few things: (a) that most visitors to your site are there because they intended to be and don't need their hand held to get to the next step, (b) that there is only one 'next step' to send them to, and (c) that your short description is a list of bullet-points as opposed to a sentence or two.

For one, I don't think we can assume the intent and understanding of most users. I visit more sites daily that I don't have a clue about than those that I do, but maybe I'm a small percentage. Secondly, depending on the product, I think bullet points can be just as effective as a short blurb (especially if you have a tagline that does a good job summing things up). Pinboard (http://pinboard.in/) is a great example of this.