Task pane, task pane, task pane
In the IIS7 UI, which is the first IIS UI that anyone can actually say "looks beautiful" ... has had a bit of a learning curve for me. I keep forgetting about the "Task Pane", sometimes called the "Action Pane" which is on the right side of the window.
There are a LOT of very useful little tasks that you might be looking for in the "main" middle pane but you can't find.
As an example, I was just examining the IP and Domain Restrictions dialog and couldn't find the domain restrictions part, well it was hidden until you enable the Reverse DNS Lookup (which is bad for performance) ... but the item to turn this on is in the Task Pane in the Edit Feature Settings action. A couple UI modules have tasks/actions like this. IP and Domain Restrictions is one of them, Output Caching is another, and Error Pages is another. These are just a handful of hte modules where you need to be alert and look at the Task Pane to really find the setting that you're looking for.
One of the things I really love about the new UI is that it shows so many more settings than were exposed before. Even settings for old features like ASP are now brought out into the UI. When I go back and look at the IIS6 UI, it really didn't have as much surface area of the IIS feature set exposed for easy administration. I'm glad we've been able to add so much richness and depth to IIS7.
Also, we finally have a forum specifically for the Administration UI. If you feel silly because can't find where to set "that setting", this is a great place to ask. If you want to know how to add your own UI (to do whatever you might want to do to ease administration ... such as perf counters, customized metrics and configuration, etc) this is a great place to ask.
Here is the direct link: http://forums.iis.net/1111/ShowForum.aspx