From the 'Launch' email ...
We expect the site to be very busy at first, and so we have taken a number of measures to make sure that as many people as possible can get their searches completed successfully. The first is that we have deliberately restricted some of the search functions on the site, meaning that the search is not as flexible as it will be later on. Secondly, we are only allowing users to download original pages, rather than view them directly on the website.
Obviously, we will 'unlock' the powerful search features and switch on image viewers as soon as possible after launch and let you know by email and via the blog when we have done this.
During launch, if the site becomes exceptionally busy, we will also restrict the number of new people entering the site. We want to allow the people who are already using the site to complete their searches rather than make the site impossibly slow for everybody. We have built the site to withstand a very large (but not infinite) number of visitors, so if you find that you are not being allowed in, please bear with us. Real-time service updates can be found on our blog, which we advise you to check frequently for the latest news.