Brilliant little helicopters, the 300'C's - proper fully articulated 3-blade rotorhead, powerful engine with plenty of tail rotor authority, nice control systems, and a reassuringly robust undercarriage and crash protection. Not fast, but flies really nicely. US Army reputedly trained over 30,000 pilots, flying 3 million hours, on the original TH-55.
Sikorsky's mis-management hastened it's demise against competition from Robinson, Cabri and Enstrom, but recent new ownership hopefully bodes well for the future.