There is a sense that the use of drones is risk-free warfare, given that humans are no longer in the cockpit. But as last week's capture by the Iranians of a US RQ-170 Sentinel shows, there are some downsides to drone warfare that don't exist (or at least, not to the same extent) for manned aircraft.
With a downed aircraft there is a good chance that the plane itself will be, if not destroyed, then at least extremely badly damaged. This lessens the ability to exploit the remains. This drone appears largely intact (Iranian TV coverage above), whether because its control was taken over by the Iranian Revolutionary Guard Corps cyber-warfare chaps, as the Iranians would have us believe, or the Russians played some part in it, as former US ambassador to the UN John Bolton would have us believe, or it simply free-fell to earth after a malfunction, as the US claims.
Regardless of how it came into Iranian hands, it is intact, and intact pieces of military equipment are very exploitable. In the case of the Sentinel it is exploitable in two ways: for the intelligence that it may have stored, which could give an insight into US intelligence-gathering capabilities and targets, and for the engineering of the drone and the sensor technology.
There are already reports that the Russians and Chinese are showing interest in gaining access to the UAV, and being the canny negotiators they are, there is little doubt that the Iranians will be demanding a high price from Beijing and Moscow. There are some claims, though, that the intelligence damage may not be as dire as imagined.
In purely transactional terms, a captured pilot is an embarrassment for the government that sent him or her, and while parading them in front of cameras is a big propaganda coup for the country that captured them, a pilot's intelligence value is much less than that of a complete UAV. It is also hard to reverse engineer a pilot, whereas Iranian authorities are already claiming that they intend to reverse engineer the drone to improve its own systems.
President Obama has kindly asked the Iranians to 'return to sender', but I think there's a greater chance of McDonald's opening in Tehran than of that particular piece of equipment being shipped back stateside.