Pros: Amazing, beautifully white teeth really fast.
Cons: Can experience a couple of days of discomfort after (zingers).
I had ZOOM! whitening treatment in 2010 and loved the results, which have been kept up pretty well by using the Nite White product for regular touch-ups.
I had a second round of Zoom! this year as I noticed that though my teeth were still white, they were not as white near the gum line.
I did experience a few 'zingers', as the little nerve discomforts are referred to, starting with the last segment of treatment, and for about 48 hours afterward. I had the treatment on Thursday, and I avoided all food with colors through Monday just to be sure I wouldn't absorb any color on my newly whitened teeth. I was told by the technician that some people experience a claustrophobic sensation having the dams in their mouth during the treatment, but it didn't bother me at all.
They do protect your gums and I did not experience any gum discomfort.
In my area, I think pricing is typically in the $400-$500 range, but I purchased a Groupon and got the service for $139. There had recently been some turnover in the dental office I used (I'd gone their for years until the primary dentist moved) and it seemed like the technicians weren't especially skilled. They referred to the manual repeatedly during the process, which surprised me as they do so many deals for this procedure and I expected them to be more experienced. Luckily I knew what to expect as I'd had the procedure before.
Please see my photos for before, during and after treatment.