I used their ORM library in a medium sized project. As the project grew, it turned a nightmare scenario. After that experience, I stick to core and raw SQL queries. I hope 2.0 brings some meaningful changes.
Since switching to asyncpg [0] these problems have vanished. It commands a deeper knowledge of actual SQL, but I would argue this knowledge is absolutely necessary and one of the disadvantages of an ORM is that it makes the SQL that is eventually run opaque.
Not sure if there are equivalents to asyncpg for other RDBMS's.