Is it safe to install themes for Windows 7?

[Andy_pandy]

This has always bugged me. I heard installing 3rd party themes for Windows 7 isn't always a good idea. I heard it can go wrong and make the OS unstable.

any ideas? I want to install theme by Stardock to make my Windows 7 looks like Windows 8 ( not the metro UI)

 

[Philtor]

Stardock are a decent software provider. Shouldn't be a problem tbh.

 

[ShakenNstirred]

been using Stardock software for years, never had a problem