I'm using Clicky on multiple sites to provide real-time and in-depth analytics. It has a widget based interface and allows you to set up unique dashboards for each site. It also has excellent reporting features, and the data is always up to date. It's one of my favorite analytics programs.
It's hard to find a negative feature about Clicky, but if I must pick one, it would be the fact that some reports are only available for limited periods, which means you can't get a one year overview of all aspects of your site. That's just nitpicking, though, as what Clicky offers is more than enough for most people.
Over the 7 years I've used it, Clicky has given me a better understanding of where my main visitors are coming from, contributing for example to a decision to create content in US English rather than my native UK English because most visitors are from the US.
Clicky provided real time stats when few others were doing so, enabling me to respond more quickly to visitors interacting with my content.
I have tried a wide range of analytics packages and I've continued to use Clicky because data visualization is clear and it's easy to generate and extract useful reports that I can integrate into wider reporting on website performance. As far as I know, Clicky provides some of the most up-to-date real time data, so that what you see is an accurate reflection of what's happening on your site. While I still use Google Analytics, Clicky is a valuable addition.
In addition to the factors already mentioned, Clicky is constantly being updated to improve functionality for users and the development team is extremely responsive. Recent updates include enhanced support for HTML5 audio and video tracking, additional visitor detail and new comparison trends. In my opinion, Clicky just keeps getting better.
There are no special resources needed to use Clicky - it works well for all the sites I've used it on, providing up to date metrics on visitors and actions. It started out as analytics particularly suited to bloggers and it's still very strong there, but I believe it can work in a wide range of scenarios.