I've installed the Vista TP v4.0 ....
... and have since uninstalled it.
It worked fine, I don't have any problems with it.
I got tired of transparent windows after a while, they're just not for me, I found my eyes hurting after a while - trust me I went through an adjusted the transparency levels several times just to see if other settings would be easier on my eyes but it just bothered them to much. You can turn off the transparency altogether which I ended up doing. The various themes are kind of nice to look at but after a while I just got tired of it and wanted my winxp classic mode back - little details like how they changed the window controls (minimize, restore down, close window) to be more graphical in nature - how does that help anyone, it looks nice but doesn't improve their function.
Here's a question, if the vista transformation pack can be applied to a winxp machine without 'killer' hardware specs and have it look & function similar to Windows Vista, why does the actual Vista OS installation require such high end hardware to do the same?