I'm not going to review or rate Merlin because I haven't used it in many years (I think 2006 was the last time I used it). At the time, there really wasn't a project management app for the Mac that had all the features I needed, so I ended up going with MS Project running on Windows in Virtual PC. It was barbaric, but it worked.
As I was trying all the different Mac PM apps, I came across Merlin. The interface was terrific, the software was intuitive, and the support was great…no wait, it was better than that. The support was awesome.
The only reason I didn't end up using Merlin as my main PM app was because at that time it didn't have resource leveling, which was an absolute requirement for me. (In checking the current user guide, I see that resource leveling is now included in Merlin.)
But even without resource leveling, Merlin was so easy to use and created such great looking graphics that I used it for my project status reports. And now that it has resource leveling, if I needed a PM app, I'd use Merlin in a heartbeat based on my earlier experience.