Pros
Core technology is legitimately innovative and very well-made. They really do have a unique and better way of writing software. Their platform could really be a really huge deal, if it is ever finished, polished, and released.
Cons
Wages are grossly non-competitive. As a relatively senior developer there I made significantly less than a fresh-out-of-college no-experience developer would make at other companies. 10+ years and they have not produced a product. Management is entirely deaf to complaints of any kind. Senior developers have a history of dramatically rage-quitting during meetings with management. (Seriously, one or two is maybe a fluke, but four or five is evidence of really serious management problems!) Significant trouble attracting and retaining quality talent. Platform is poorly documented and hard to use, because management can't seem to keep talented enough developers around long enough to do that. Charles (the owner/CTO) is impossible to work with, and does not act on any feedback of any kind. No meaningful quality control or review processes, developers are not properly supervised and spend large amounts of time working on code that is thrown away. No meaningful planning or design was done for the product. No coordination between teams existed. Developers are regularly kept in the dark about important details, like what the product they were developing actually is and when deadlines are. Developers with very little experience (sometimes nearly straight out of school) and with no demonstrated leadership or technical ability are promoted to management / lead positions.