HSP is quite OK, but it is entry level. Super fun though. HSP LiPo Electric Brushless are also worth considering, in lieu of Nitro. Quieter, reliable, and less maintenance.
HSP v's HPI is like a WRX v's a Porsche... Almost as fast, just cheaper finishes and parts!
My HPI is insane fun... Flies along at ground level, and flies through the air. Amazing control in the air, and perfect suspension for landing...
LiPo HSP is roughly $200, 4wd. With batteries.
LiPo HPI Blitz is roughly $440, 2WD. Add $100+ for a good battery and charger.
The Blitz is faster, looks heaps better, and is slightly harder to drive as a 2WD, but more rewarding... The rooster tail wheel spins are amazing!