Very easy to use interface, very fast response time for issues that arise.
Nothing so far! They do all of our DNS hosting with great customer support at fair rates. We have an existing client base from other companies who are looking to move up-market but we need better control over what they can access in their account than just being able to change passwords or create subdomains. This solution was perfect for us as it allows them total flexibility while giving full administrative power back to ourselves.