The ease with which I can build an application that runs as fast or faster than equivalent Java code - without having to write any java! And it's free too. Not much so far but there are some things like saving files via FTP etc. where you have no choice other then using their API (which works well). It would be nice if they had more examples/tutorials available online rather than relying solely upon what comes up when searching through Google. This makes me feel somewhat "locked" into this platform. We use polyhedra for our main data processing system at work. Our customers' requirement was very specific; we needed something quick & dirty that could run quickly enough to process large amounts of data within reasonable timeframes whilst not requiring us to spend lots of money building custom hardware solutions from scratch.