After coming from the n5 back to Samsung, I actually like it. With stock Android I missed some of the features Touchwiz brought, like being able to swipe and immediately text someone from my call log without having to tap 3 or 4 different things.
Also, I had trouble using Gmail exchange for all my email accounts and didn't like it at all. Regularly had emails resurface as new after I had deleted them.
Stock Android was great, but I felt it lacked some nice features. That's not to say Touchwiz doesn't have too much going on, but I didn't feel stock was perfect.