I've got a very simple website that my brother-in-law wants to be able to edit the content of. I looked at various CMS, and Umbraco seems like a good fit, but I've never used it before. A brief trial looked good, but wonder if anyone has had a bad experience with this when used in the wild.
I don't know if you're only taking ASP answers, but I've used GetSimple CMS recently and it was perfect for making a small CMS.
The entire site was made and polished in about 5 hours from design.
I have never used Umbraco or heard anything about it. Oxite is another simple ASP CMS that you might compare Umbraco to, though I haven't used it either. Just offering another option.
I have also never used Umbraco but I have used Wordpress and Drupal. I think both are very simple to use with large community support. From your comments it looks like you are only interested in ASP .NET solutions but if you are looking for simple, you might want to consider Wordpress or Drupal.
I have used Umbraco for a client site of mine. It wasn't my original choice, but they had experience with it so that is what we used. It was very simple to install/create content/edit pages. I would def recommend it.
This is the site: Neatco.com
Feel free to contact me if you have any questions about it.