Part of me wants to have an immortal character, but the other part thinks it would make the game even more easy & boring than it already can be.....
I wouldn't want to be immortal every game. There are some donwsides to it, which is nice. I've already lost an eye and a hand to disease. I'm no longer ambitious. I haven't had control over my dynasty for a century (my current heir is some greek duke who is my great-great-great-great grandson). I can't change my succession law ever again. I haven't lead troops my entire life. And you start getting pretty paranoid about being murdered (Hashashins already killed two of my councillors, and now there's apparently a plot to kill me as well). Also, my witch-wife is celibate, but otherwise I probably would've already had far too many children.
On the other hand, my realm has been very stable because of the long reign bonus. You can also take the prosperity ambition every ten years, and the stewardship you get from that stacks.
It's worth it at least once. And it's not something you can try on a lark. Either you have a very good character, or you fork over tons of money. So if you don't really want to become immortal, it's not something you just do "because".
What I would love to see is more stuff (and maybe I haven't seen it yet, but it's already in there) where your character suffers because of their immortality. Going insane, losing touch with their humanity because everyone you knew has died and it gets harder and harder to sympathize with ordinary mortals, vassals and dynasty wanting to kill you because they think you're an abomination, the mist of the ages starting to make you a less competent ruler the older you get, stuff like that.
It feels weird to say "immortality is OP pls nerf", but usually in fiction, immortality is the prime example of the Hubris of Man, and defiance of the natural order. In fact, the oldest human story in existence also touches on that subject. And it feels weird that you get immortal, and everyone else in the world just goes along with it. No jealousy, no zealousness, no one even seems to know, even though you're 180 years old.
But besides that, it's pretty cool! The event chain I saw was awesome and well written, and it seems that that was only one of a few possible storylines, so I definitely recommend checking it out!