Well. Here's some international reaction that semi-promised.
Excerpt from The Inevitable: Politics in the lead up to WWI
Serbian War: Reaction
While the Austrian and Serbian reaction to the war was relatively mixed, the reactions of the other great powers varied greatly:
Russia was absolutely livid. They had last two potential allies, Serbia had gone firmly into Austria-Hungary's camp. Bulgaria would stay neutral, and would probably wait to declare independence until the Great Powers were distracted.
This completely set the Russians back in the Balkan Peninsula. All the countries there were one of three things; Neutral, Allied to Austria-Hungary, or Austria-Hungary itself! Russia set about building a covert team to infiltrate the Balkan countries and do whatever was necessary to curb Austro-Hungarian expansion.
Nippon took advantage of Russia's distraction to plan something big...
Italy was less than impressed with the Austrian actions, but believed (to an extent) their claims that it was all just a 'happy accident'. They made plans for war on Austria-Hungary though, just in case.
France was somewhat annoyed. They made a few attempts at allying with Greece and Bulgaria, only to find that Austria-Hungary had begun beating them to the punch in the latter, having guaranteed it's support should Bulgaria declare independence. Greece opted to remain neutral.
Deutschland expressed positivity to the idea that an ally was asserting itself.
Britain was glad Russia had been effectively kicked out of the Balkans, but was mildly worried about Austria-Hungary's mild revitalization.
America was neutral on the matter. On one hand Austria-Hungary had effectively expanded into the Balkan Peninsula. On the other hand, they had stopped Russian expansion and secured an ally, possibly reducing the powderkeg potential of Balkan countries. But perhaps not...