Amazon released the Kindle for Web Beta earlier this week. When I visited Amazon to try the product out, I couldn’t find the feature. Like Waldo, it was hidden among hundreds of other details on the page. The product release blog post indicated the feature was in a green box. (It’s the Read First Chapter Free button).

Searching for this feature, it struck me for the first time that Amazon’s product page is hopelessly crowded but it works because Amazon’s user interface has been designed for repeat visitors with consistent workflows.

This morning, Joshua Porter blogged about designing to build passionate user bases and described the development process using the graphic below. He rightly posits that there is a time in the design process to build for regular use. Amazon is very much in that stage. To wit, each time I visit an Amazon product page, I do the same three things: determine if there’s a kindle version, evaluate the distribution of star ratings, and read a few of the best and worst reviews. Then I make a decision about whether to buy, pass or add the item the wishlist.

However, with such a crowded UI it becomes difficult to determine which elements on the page are most valuable, even to experience users. When launching new features in such complex UIs, user education is a significant barrier to adoption.

At Google, we found that many feature launches would result in less than 10% adoption. Most new features weren’t broadly applicable, but setting that aside, it proved to me that changing user workflows is extremely difficult – particularly in highly crowded user interfaces. Overall, Amazon’s interface works. I’m certain they’ve tested the revenue impact of launching the green box. But Amazon’s interface is close to a local minimum in effectiveness. There is too much information to digest and not enough focus on the task at hand – educating the buyer to encourage a sale.

If your startup is iterating quickly, looking to change user workflows and understand key user behaviors, keep the interface simple and clean.