I am very happy with weight and feel of the S4. Metal is obviously better but obviously heavier.
It's amazing the technology they have managed to squeeze into that chassis. I like it lots.
It has many improvements. Temperature, pressure, humidity sensors. In built pedometer which is handy, the screen is the best out there.
There are so many things that people are labelling as gimmicks that simply aren't, and add to the over all usability of the device
What is useful to one person is bloat to another. I used an S4 at an AT&T store, and yes, I can say (for me) that Touchwiz is bloated and gets in the way of a good Android experience. Coming from a stock Android experience (ala Galaxy Nexus), I found Touchwiz to be extremely convoluted.