I produced some video tutorials for LightZone and worked with it a lot over several versions. What I have to say is based on a version that's at least a couple of months old.
I do agree that the ToneMapper tool is nice and tried to persuade them to make it a separate add-in. The problem is that the code is entirely written in Java, and the technical architect has strong reservations against add-ins because they do not make non-destructive edits. I tried to explain that I use lots of add-ins non-destructively by creating a Merge Visible layer before I invoke the add-in.
I also like how easy it is to make selections and even adjust them in later editing sessions. I urged that as my top wish for a Photoshop add-in. No question, it beats the heck out of the pen tools in Photoshop.
They consider their product superior to Photoshop. I worked long and hard with the product, and I found the product not to equal Photoshop in terms of tone and color adjustments.
I found LightZone to be very prone to posterizing images. With Curves, you can make very pinpoint adjustments to tone and color. It is like a scapel. Yes, the Curves interface is not so intuitive at first, but as most of us know, after you work on a few images, you become proficient with it. I worked with a number of my images from my Bryce Canyon trip where I slipped and fractured my spine last Feb., and I could not make sufficient adjustments in LightZone without visible evidence of posterization.
I found the Tone Mapper interface to lack sufficient granularity. At first blush as you push the zones around, you appear to make tone adjustments quickly and easily. It's when you sit back and use your critical eye that you start to see visual evidence of posterization. I find Curves in Photoshop to be a scalpel and the ToneMapper in LightZone to be a butter knife in comparison.
You have to keep in mind that the zones in the Tone Mapper are very broad. So you typically end up significantly expanding/compressing some of the tonal ranges in your image and that invites posterization.
I want to be clear about this point. I'm not talking about the histogram looking toothy. I'm talking visible evidence of posterization. I don't worry about whether my histogram has gaps *UNLESS* that results in visible artifacts, and then it's those artifacts I care about.
I hope they have improved the Noise Reduction tool. In the versions I have, I could not get the tool make any significant reduction in noise.
The technical architect suggested that you could get that greater precision by using multiple Tone Mapper layers. Perhaps, I didn't have the patience to try that. I failed to see the advantage of using multiple Tone Mapper layers and fighting posterization when I could use a single Curves layer in less time.
I'll disclaim my own conflict of interest. I no longer produce videos for LightZone. They wanted me to make claims to which I was uncomfortable lending my voice and my name as the producer of the video. Their point-of-view was that their technical architect was the editor and editors rule. My point-of-view is that creative talent do not make claims they believe to be exaggerated or untrue. It was very tense as I sought to reach compromise on those claims. We parted amicably enough after all that stress and I was paid for my time, so I do wish them well.
I like Uwe a lot and have contributed to his site, but it is important to realize that Uwe is marketing LightZone. My guess is that he still uses Photoshop for his own art prints. I'll be very interested to learn that he finds LightZone to be so useful that he now prefers it for his own work. (None of this is a personal attack on Uwe. I just do not trust reviews when people accept banner ads and even hawk that same software through their site. That's true, even when they are someone whom I respect, and I do have a lot of respect for Uwe.)
I would like to post a review on my site. My policy, however, has been to do independent reviews (i.e., I buy the product and have no business relationship with the manufacturer). Since my copies of LightZone were given to me and I had a previous business relationship with LightZone, I have not written that review.
What I've written here is the essentials that I'd put in a review.
In conclusion, I love the selection tools (which they call regions) and wish they were a separate add-in for Photoshop. LightZone, IMHO, is not even close to a replacement for Photoshop. It does not have the breadth of tools or the flexibility that Photoshop offers. If you do not need all the features in Photoshop or the considerable learning curve for Photoshop intimidates you, I would suggest Photoshop Elements over LightZone. The talk about the Ansel Adams "Zone System" is not even true to the original. As the technical architect pointed out, LightZone is "based on" Ansel Adams "Zone System". I would argue it is very loosely based on it, and that alone is not a sufficient reason to prefer LightZone over Photoshop.
I do suggest people download the free trial, if they're interested in LightZone. I have a very critical eye for things like posterization. You might be very satisfied with the results from LightZone.