Only one missing feature don’t allow me migrating from phpmyvisites to piwik: the summary.
In phpmyvisites, we can get a summary page with some basic statistics of all websites, and this is very usefull (essential?) for managing a website network.
I hope this feature can be quickly added with reasonable work time.
I’m not sure if the plugin being worked on in this ticket is what you’re looking for, but it might be worth checking out. http://dev.piwik.org/trac/ticket/455
Currently it’ll give another tab with “Sites Summary” that shows every site and how many visits, page views, unique visitors, and evolution for the period you have selected. The only feature I wish was added to this was summation of all the numbers at the bottom for all the sites (maybe sometime I’ll look into it myself and see if I can add that, although I’m not much of a dev).
Actually it isn’t really hard task.
For http://cnt.cajax.net/analytics i’m just running same query for all sites and counting total results.