DotNetSlackers  creator Sonu Kapoor writes  about Ajax.NET Professional :
"In one my projects, I needed to use some Ajax functionality, so I thought I should try out AjaxPro and see how it works. I was suprised to see how easy I was able to intergrate it into my project. I had few problems here and there, however Michael  was able to quickly help me out.
[...] Everything works now like a charm. I am very happy with the end-result and my boss appreciated it as well. I can only recommend this Ajax Library to other developers. I am looking forward to use it more often in my future projects. [...]"
Do you remeber DotNetSlackers? Yes, they won  the Microsoft ASP.NET AJAX Mash-it-up contest Grand Prize with GeotagIt ! They are also listed  at the ASP.NET AJAX showcase.
So, feel free to give Ajax.NET Professional a try and make your own opinion.