I'm really excited about this new open-source web analytics system. The loosely-couple architecture is brilliant, meaning you can swap out components as needed.
One example I've already found is the limitation of using CloudFront as the data collector. It's very easy to set up, but limits you to GA-style first-party cookies and an inability to reliably track across domains. I'm already planning to write something in NodeJS to replace this component.
There's no GUI, but it's incredibly easy to set up data collection and just start collecting. Unlike ordinary web analytics tools, you're collecting everything. Tools like GA and Omniture throw away things like full URLs, full User-Agent strings and full referrer URLs, which means there's some times of questions you can't answer unless you were capturing the data the right way from the beginning.
As an example, I recently got asked to analyse our on-site search. Some of the searches are recorded in SiteCatalyst, but other aren't. Even though the keywords are included in the request URL every time, we're bang out of luck doing any keyword-level analysis on historical searches. If we had something like this recording data, the analysis would be tricky but possible using Hive.
Very cool stuff. If you're reading this on my blog site, you're already being recorded to it.