The link Greg posted above is to date the working repo and state of the php-cql driver efforts.
While a driver is not yet available it does not stop you from using CQL, the drivers are all going to be a wrapper of the thrift method "execute_cql_query" (Until a new transport is created anyway).
That means you can simply compile thrift for php or get it from an updated project and then pass your cql query to that method. It does mean manual handling of things that a driver will/should take care of.
"Is it just a more sql-like way to make queries?", basically...yes. One of the things that came up on the Cassandra mailing list was getting CQL to be as SQL-Like as possible.
"What is the benefit using the CQL?" Well, mainly that some new Cassandra users find the thrift API tedious to get to grips with, CQL may be much easier to learn since its is so close to the "normal" sql.