I've used it a lot and it works very well. However, at present I'm using stock Ubuntu 12.04 with the studio (mostly music production based) applications loaded through standard apt-get means. In the past Ubuntu Studio packaged a kernel built with Ingo Molnar's low-latency patches, but the stock kernel is good enough for real-time, low-latency production these days. Other than having most of the applications that you'd need packaged for you - a valuable service for new users - I'm not sure what Ubuntu Studio brings to the table for experienced users.