I have been a big fan of GRG enjoying both Sengoku and San Angelo immensely, so I may be a bit biased. The system is easy and quick to learn, especially those coming from the HERO/Fuzion end of the spectrum.
This is simply a solid system that I do not think get enough breathing room in the crowded realm of game systems. I have used this system for pre-WWII pulp and Western - both did very well. I would not want to use this system with high fantasy or superheroes as there are other systems better suited. For normal to heroic is where this system shines.