We use it in all of our environments and it is extremely flexible, mostly reliable, but still feels like a hodgepodge of plugins and various components. Once you throw in a variety of build tools and deployment options etc, it can get rather unwieldy. Still, we use it for almost everything now (no forgotten cron jobs running on random servers) and it gets the job done. I often think we should investigate other options, but we have made such an investment at this point it would be a massive undertaking to move to something else.