I used I-Biz for about 6 years on my Prelude. Everyone used to comment on the shine. People who'd never seen my car asked if it was new. In the end, it had 128,000 miles when I sold it.
I-Biz is very quick and easy to use. Simply wipe it on wet and wipe it off while it's still wet.
It gives a decent shine but it's not very "deep".
It's my understanding that I-Biz can not be layered.
Over the 9 years I owned the Prelude, I tried LOTS of over the counter products. I-Biz was the clear winner in both shine and ease of use.
When I bought my new car, I started reading up on Autopia and discovered that I-Biz may not be the best stuff out there.
I started using Klasse on my new car (and will soon be adding Platinum and P21S). From what I've seen on my own cars, Klasse is CLEARLY better than I-Biz in the shine and durability departments.
And given the reviews here (not personal experience), I'm sure that a lot of people's favorite products here (Zaino, Blitz, Blackfire, Souveran, etc.) would all be better than I-Biz.
Overally, I wouldn't say it's a bad product. It's certainly a good product. But there are definitely a lot of products available that are superior.