Rackspace Cloud has a very nice and cozy small forum for all their customers and users to submit and vote for ideas and feedback, such as features they want but are currently not available, or improvements / fixes that need to be done to make the cloud a better product.
Check out the feedback forum here: http://feedback.rackspace.com/
You can read through all the ideas and requests as well as the comments to get an idea of what Rackspace Cloud is like and how it is doing in the eyes of their current customers and users. How the company is responding to these invaluable input is also an important factor in deciding to go with them or not.
A great move by Rackspace.