A few years back I had some experience using this tool to migrate a MySQL database to a PostgreSQL. As far as I remember it was quite pleasant.

I had the some trouble with MySQL accepting invalid dates (like 0000-00-00) while Postgres rejects such dates. However, there was an option to convert such dates to NULL which saved the day.

Also you have to manually rewrite your views. Since we had a lot and also very complicated views I ended up materializing each MySQL view, manually porting it to Postgres and then comparing the result. That worked quite well.