I have no idea what Touchwiz is, but I can confirm that this phone is beast. I will say that when it comes to messaging, my N5 was generally more snappy with my inputs and such. However, it's nothing that breaks the experience.
I'm probably going to order a case overnight on Amazon since I'll be traveling to Disney next week. I want my phone at least somewhat protected in my pocket.
Also, this screen is ridiculous. Like, it's so disgustingly good. I finally feel like I have a screen that's worthy of watching videos on and reading books/comics on. This thing is going to be cray cray.