Is this indictment of DevExpress WPF controls valid and what is a good alternative vendor?

Abject frustration is EXACTLY what I experienced thanks to DevExpress. I lost hours of my life attempting to simply bind a combo box. The drop-down list at best would only display my ItemsSource class name multiple times. I even posted a StackOverflow question to figure out what I could possibly be doing wrong. Finally on a whim I tried removing this one line of xaml:

devx:ThemeManager.ThemeName="DeepBlue"

Suddenly my problem went away. It was caused by the Developer Express wpf theme DeepBlue. Discovering the problem was a tremendous relief. My company will now be using Telerik WPF controls. My colleagues are quite happy with DevExpress Asp.Net controls. It is only the WPF suite we are avoiding.

I would like to clarify our opinion on usage of our controls in applications built based on the MVVM pattern. At the moment, we are working on a series of examples which should clarify how our controls can be used under different popular MVVM based frameworks (like Prism, MVVM Light and so on). There are a couple of problems in our WPF controls regarding the MVVM pattern and we are trying to eliminate them. However, generally there are no showstoppers that can prevent a developer from using our controls in a MVVM application. Hopefully, our examples, posted on the DevExpress Web Site will convince you in this.

I do not agree completely with the assertion that DevX developers missed the mark on WPF. However, I will say that it appears they may have had a steep learning curve to overcome. Lets face it, WPF is massive. To master it, even out of the box, is a daunting task. I do agree that DevEx controls will not fit into a MVVM pattern, but they do sit quite nicely in a MVP pattern. "Can you suggest an alternate vendor of WPF controls?" No, but I will suggest that you study additional patterns if you are stuck with DevEx.