I love the difficulty and I haven't yet seen a run fail, so I feel like the tuning is fine for normal. There's nothing wrong with being on the floor on your first time.

However, many people have echoed my sentiments already. The only new thing I would like to add is this tweet about Arcadion from @divisionten (Sara Winters) on Twitter. They are a legally blind player with partial vision, and here is what they had to say:

Arcadion accessability talk (non spoiler): I have so far only did M1 and M2. The fights are fair and for the most part clearly marked. There’s some mechanics that fully blind people cannot do (because personal responsibility) but both fights are clear and easy to read so long as you have some useable vision. Mechanics are high contrast (eg M2 is pink on blue) even if you can’t see the details. The fights are hard, especially since many are coming in just AF gear. The tier will be easier once people get raid and tome gear and start creeping up to 710-720+. We almost hit lockout on M2. I figured out the mechanics quickly and was able to sight read but I do hard content. If you can do these, you can clear P1S synched and many older EX. TLDR: tough, but very fair.
If they think it's fair as someone who is legally blind, I think that says wonders about the balance of the content and I really respect their views since accessibility is important.