The stuff built for finance is definitely interesting. John and I (two of the people working on this) previously worked at a fintech startup and worked with a closed source time series db called OneTick. It was super fast, but its API work for analytics/events use cases. Great for fast moving market data though.
I was trying to recall the name of OneTick ... It does work well for market data (especially with corrections and stuff), but is not a convenient general database.
kdb+, on the other hand, is a time series database that works perfectly well as a general database, with a query language that is at the same time infinitely simpler than SQL and yet much faster, more expressive and useful. There's a learning curve, it is steep, but it is well worth it.
