The Clustering feature alone makes it worth the price; everything else is icing on the cake. The UI is pleasant. It's great for keyword clustering and topic research.
Few suggestions:
-Page-level link metrics instead of root domains for keywords.
-Link metrics for individual keywords and not just the seed keyword.
-Display keyword positions when extracting keywords from domains.
-An option to import and cluster keywords from third party tools while keeping the search volume and keyword difficulty (KD) intact since Writerzen doesn't have an inbuilt KD for individual keywords.
-Detect similar domains for keyword extraction based on seed topics.
-Highlight easy to rank keywords (like those with forums in search results).
-Display SERP features (like featured snippets, ads, videos).
-An option to copy selected keywords to the clipboard instead of exporting them.