Piwik is awesome, it is for sure expandable, but this is a matter of time i think, so keep on working!
Especially the campaigns are really helpful, even if theys not as complex as the one from google analytics, but this isn’t so much important. It has nearly everything i actually need.
But it’s a bit complicated to generate a piwik-campaign prepared url by hand, so i wrote a small tool, which is now online for everybody who’s interested. It adds the piwik GET params to a given url, you can choose two existing camaigns (twitter & facebook) or a custom one. And the campaign keyword is generated automatically from the given url, but it can be customized too.
So, feel free to get a look - but it’s only in german language. If you think an english translation would be nice, just give me a note
Feedback would be really awesome