While it wouldn't exactly be heartening news if the F-35 did have to see combat, it would put the multi-role stealth fighter's many technological systems to the test. The B's clever STOVL system is its centerpiece, letting it operate from Marine ships and bases that don't have the space for conventional aircraft. It's also a pioneer inside the cockpit, with giant touchscreen displays and an in-helmet display that replaces the conventional HUD. Basically: where the F-22 is a relatively familiar design in some respects, the F-35 is more of a clean break.
The Marines will eventually field 420 F-35s, 67 of them being the carrier-oriented F-35C. They should eventually replace combat aircraft ranging from the Harrier (the original VTOL combat jet) to the Hornet. Not everyone is as thrilled with the design, though. Its development was plagued by numerous glitches, including software bugs and hardware design flaws (including one that led to a pre-takeoff accident). Also, cost overruns and high prices have led to scaled back orders. The F-35 may be a technical marvel, but there were many, many sacrifices involved in putting it into service.