Everything I experienced during Wikimania 2015 has been documented here. Please, have a look!
As a summary I can say that it was again an enrichment for me and hopefully for those I have the opportunity to talk with. I discovered new tools, I learn about the future, took a lot of input for future projects and also for the organization of a chapter and look forward to attending next Wikimania edition.
I met again lots of different people all over the world and could finally put a face to same people I only new over the Internet. I also had a chance to discuss with some WMF managers as I am always curious whether the breach between community and Foundation is as big as some people affirm.
Apart from minor organisation flaws I think that we have to focus more on the programm and help both, the speakers and the public to look what they are looking for. As the organizers of next year Wikimania are aware of this I am happy :)