Ask HN: did anyone try MySQL's new online DDL (alter table)?

I'm wondering if anyone had any experience with MySQL's online DDL (alter tables) since it was released (version 5.6)?

Since this is a rather sensitive operation on the DB, I'm interested if there are any pitfalls or other things to be aware of. I didn't find many recent reviews of this feature.

http://dev.mysql.com/doc/refman/5.6/en/innodb-online-ddl.html