Following on what Salar has said and I agree with him 100%, I also have worked with the menu. Component Art has it's own issues, which made working local and live a bit of a headache, and these companies, and how they wrap their menus to work with DNN is hard for me to follow becuase Component Art does one way, Telerik does another and http://www.devmansion.com does another, but entry point for someone to come into Dev Mansion is way more cost effective.
My issue with these menus, and I'm not trying to give them a hard time, because they really look superb, is if you use them with extensive menus, the weight of the page absolutely skyrockets. Instead of the JS code like in SolpartMenu, I have seen an enormouse amount of code be displayed in the source code, which on one occasion, asked me if I wanted to continue loading the page.. I've never see so much code dropped into the content.
But in fairness to Telerik - you can download a complete build and work locally to test, I just find it hard to deploy and show clients because I haven't invested in a license. I have found Telerik have been supportive to a point, but for some companies, just as component art, it's a very small part of their business model, so I guess we're lucky we even get a look in by comparison to other products.
Not only do you need to know CSS, but you need to understand the several areas the menus need to be changed, whether is't in the skin folder, or the dataprovider folder, or the controls folder, wherever they have put their files. I'm always looking at these products, but until I can justify the licensing to test, I'm working locally until I also have a client who is really set on using third party components.
The menu in DotNetNuke seems to me to be the biggest time factor when developing sites.. at least from my perspective.
Nina Meiers