It’s a fun dungeon. It’s pretty mechanics-heavy, so I definitely wouldn’t start with hard mode. 
Some of the fights aren’t much harder, but some are.
It’s also really long right now (8 bosses). The first few times I did it, not long after it was added, my groups either didn’t make it to the end or came back a second day to finish it. If you wait until they split it like they did Mechagon, you’ll be able to run just 1/2 at a time. Or so I assume. I’d expect 9.1.5 or 9.2 to do that.