It is definitely more finance oriented, though Kx are making moves towards other application areas. Another difference I'd highlight is that Kx concentrate on the core database itself, esp. performance and expressiveness of the query language, and leave things like GUIs and admin add-on tools to partners (like first derivatives and aquaq).
kdb does just fine with metrics and sensor data. Personally, I would argue that it's weaker on string handling though, which can hurt in certain use cases.
I doubt it'll go open source any time soon. However, it being around a long time is something salescritters can spin to wonderful effect re stability, support, etc etc. ;-)
I think there are fine application areas in finance that you should consider -- just consider the many areas where the core problem isn't related to juggling TB of market data ticks coming off the exchanges.