I think it all depends on what you want out of your phone. Have you used a "true" Android experience? Do you know what you'll lose/gain? Some people care, some don't.
I personally don't think I would, but I tend to like some of Touchwiz's features (like the camera and some of the motion controls). I use a different ROM (CleanROM) but it's still Touchwiz based. And I've installed Nova launcher and WidgetLocker so I don't really have a Touchwiz experience from a UI perspective, but still get the Touchwiz features that I like. If I want a vanilla Android experieince, I can get a ROM for that.
Even if I had vanilla Android, I'd probably still be using Nova Launcher and other customization apps anyways.
But each person is different, so what works for me...well, you know.