Not to dispute RPM's legit comments, but the JSF will be better than the harrier primarily due to SOFTWARE enhancements. The Harrier is a great aircraft but it's limited by the control feedback system. It's mostly analog, routed through a human brain. That, combined with the single-engine design, means they're going to lose a few each year. Compare the harrier loss rate with the F-16, and you'll see that on average we lose only a few more harriers each year than F-16s. Guess what - the JSF is also a single engine fighter so no matter how advanced the jet is, we'll lose a couple every year to engine failure.
I won't go into details, but we've had half a dozen incidents in the last year here at Lakenheath that would have guaranteed resulted in aircraft losses if they'd happened to an F-16. All engine related problems, all unexpected or unavoidable, all recoverable because the F-15 carries a spare.
I found it amazingly lucky that the harrier shacked the precise intersection between 4 backyards and an alleyway. One lucky dude gets a new swimming pool courtesy of the USMC, and nobody needs their house rebuilt. Damn lucky if you ask me.