Kudos to Green Ronin for the price reduction on this the best of OGL core books. I already had the print copy, but couldn't resist the pdf for $10. Though the role books, especially the Adept's Handbook, add depth to the system; honestly, an experienced gm could tool his or her game with whatever he or she desires using just this pdf and conversion from freely available OGL sources, like the 3.5, Modern and Mecha SRDs alone [conversion guidelines included]. But don't let that stop you from exploring the great 3rd party material available for this system. I gravitated to True20 recently too because of the good quality of fan-produced material available. Give it a shot!