This is not such a disaster. In WPF your are either a designer or a developer - both if you are lucky. The most important thing is that he gets the application working correctly and the code stable.
jh71283 and
Bas should be all acquainted with resource dictionaries. All the chap that developed this app needs to do is go
here and choose a theme (or two). Within a flick of a switch the whole application will be looking respectable. Trying to do this with pre-WPF technologies is a lot of hard work. If you are a very good developer and lack WPF design skills the system makes it easy for you to still be effective.
I've been thinking about making a reflection based application. If you look at reflector at the moment, I hate the way you navigate. Look at this traditional tree view

Now look at it after some WPF goodness

This simple article by
Josh Smith shows the power of WPF and how you can re-order traditional controls like the treeview and come up with something different.
I will probably do the reflection application in WPF because the door has opened up insofar as possibilities, and just the fact that you can buy or get resource dictionaries developed that can affect the whole application makes it something Redgate the new owners of reflector are unlikely to do. I also think that there is a "new breed" of developer that expects to be able to navigate hierarchy based applications much easier.