Review (4/5): I like this but...
My only complaint with Zest isn't unique to that product: it has to do with the downsizing of consumer products so companies don't have to raise their prices; they just give us less.
Zest comes in a 4 oz bar, common in most "bath sized" bars but smaller than I remember bars of soap when I was a younger man. The smaller the bar, the easier it is to drop it when it's wet.
If you get beyond that, Zest has two strong positives: the scent is pleasant without being overpowering. It is appropriate for men but I don't think women would object to using it as well. Also, it appears to be less caustic when you wash your face around your eyes. I made the mistake of getting Coast Soap in my eyes once and almost had to see a doctor; this is much milder.
The bottom line: I will continue to buy Zest and will keep whining about small bath bars. This is a decent soap brand.
Update: I originally wrote this about the 4 oz bars and the review somehow got applied to the larger 5 oz bars as well. Please allow me to make this clear: the 5 oz bars answers all the negatives I had about the smaller bars. This is finally what I've been looking for and I couldn't be happier with the larger size. I highly recommend it.