I've been playing around with WriterZen to see if it could replace Frase as my primary content creation tool. Honestly, I don't think it's there yet. (Though it's better than nothing if you weren't able to get in on Frase.)

Before I get into the negative stuff, I will say that the topic discovery tab is pretty useful. I was able to find what looks like a pretty good keyword almost immediately, and I'm pretty picky on what I'll write about because I have very little time and have to make every article count. Not sure what it's doing with the "ideas" because they seem to be all over the place, but the page as a whole is a winner.

The keyword research page is also very helpful and lays out most of the information you would need in a useful manner.

Here are some areas that would need to be improved before I could use it full time:
1) Plagiarism tool is hot trash. I plugged in an article that I know the writer plagiarized major sections of (in some cases almost copy pasted), and on high it came back as 67% plagiarized because phrases like "how to do it?" and "coffee grounds are" were used in other articles somewhere on the internet. On medium, it came back as 96% unique. Quetext doesn't catch everything, but it catches the main sections that were ripped from other sites, even if the author changed a word here or there.
2) Once #1 is fixed, the plagiarism word count limit should be at least doubled. My shortest articles are at least 1,000 words, and an article shouldn't have to be broken into multiple pieces to be run through a checker on a paid tool.
3) The content creator (the main piece I use in a tool like this) is off to a good start, but it doesn't put all of the information at your fingertips in the way Frase does. In Frase, you can scroll through the articles in the serp using the "top content" tab and see all of their subheads. If you want to take a closer look at one, you can just expand it and see a summary/excerpt of the content written under that subhead. This lets you scroll through and see everything being recommended on the serp (for a best x for y post) without having to open and read all of the articles. WZ tries to do this, but it feels clunky, doesn't have as much information available, and subheads often come out with HTML/JS code in them.
4) It really needs NLP so it can compete with tools like Frase and Surfer. Having a few keywords is useful, but it lacks the depth of the other tools. Also, having a "topic score" that measures relevance based on the NLP terms pulled from the top ranking articles would be useful as well. This would greatly help with content optimization.
5) The keyword research tool is extremely slow. I looked something up before I started writing this, and as of the time I'm submitting the review, the insights tab is still spinning.

Overall, I like the tool, but it does need a few things improved before it can be used as a primary tool for anything other than keyword research.