How many negative messages does it send out? Let's leave aside, just for the moment the fact that none of our soldiers, sailors or airmen should be there at all because the whole conflict and invasion is illegal, colonial, rapacious, cynical and just plain wrong.
Here are the two negatives that I've immediately come up with, blood boiling and steam whistling from my ears.
Negative message one: the government is perfectly happy to allow the army to pay a soldier who cannot do his job. Prince Harry cannot possibly claim to be a "real" soldier after this; he is purely ceremonial and nothing more than a toy-soldier mascot, unworthy of being paid to do a real soldier's job. Next time the young twerp or any of his ridiculous relations is seen "inspecting" some troops with bogus medals on his puffed up chest, just remember - they are not soldiers, they only play at it.
Negative message two: it appears that it's perfectly OK to send ordinary working class young people into a situation that's "too dangerous" for precious little Harry. So ordinary folk can be maimed or killed after swearing an oath of allegiance to the House of Windsor and donning a uniform, but the blue-blooded stock to whom they swear are to be kept away from all harm no matter what (even though they might be being paid precisely to risk such harm). It was ever thus - let the poor and weak protect the wealthy and powerful, so they can continue their pampered and inane lifestyles whilst the underclasses are kept subdued by some misplaced sense of "patriotism" or "duty". Arse.
"...The old lie: Dulce et decorum est
Pro patria mori"
...unless you're Harry Windsor.