The modulation matrix is quite good. The modulation info is right there in the matrix and it works well, not eye candy but a tool.
The sound is very good, it is not a problem creating sounds(or using the tens of thousands of patches from the internet) which will hold their place in the mix.
This is the low-price way to use all those classic DX patches and a practical way to get some modern FM madness going on. I prefer the sound of FMHeaven to the "competition" for classic FM work of the sparkling, metallic, sweet or nasty kind. True FM has a wonderful ability to create "phyical" sounds as the sidebands can be quite complex.
This is a very good and useful softsynth.