Atomicity of batch updates

[Artem Orobets]

Hi,
Wiki says that write operation is atomic within ColumnFamily 
(http://wiki.apache.org/cassandra/ArchitectureOverview chapter "write 
properties").
If I use batch update for single CF, and get an exception in last mutation 
operation, is it means that all previous operation will be reverted.
If no, what means atomic in this context?