The sign up process is slick but way too long. Need to provide some instant gratification.
Just because I like to check out new products, I was patient and did all the steps properly. But, in the end I just got a blank screen saying "this list is empty". That was pretty disappointing. Then I imported my Instapaper articles and still the list is empty.
If speed is an issue, why don't you just show me "today's popular articles" or just fetch the last 10 links I shared on twitter? Show me something or I might never come back. This is not exactly a space without competition.
Edit: I'd like to be able to save articles with a single click. The 2-click save thing is what everyone gets wrong and why I end up using Instapaper for all my bookmarking.