Sorry about that -- I couldn't speak as much about our Hbase experience, but I can speak to the toll its taken on our ops team so far, which is very high, with lots of crashes.
To clarify, we've had lots of region server crashes, mostly due to our own data model and generally not as a result of any intrinsic fault of HBase. To my knowledge, not many of these (any?) have actually resulted in a total HBase failure. The system generally degrades as it should.