"Worth" is totally subjective.
Here's what it includes (for those who don't know)...
The last two cruises we've been on (2022 & 2024), we were among the first to board and we didn't have the Key, so that marks off #1 for us.
The reason I carry things on is to make sure I have them with me (valuables... electronics, meds, etc). If it was something I felt safe dropping off with someone, I would have left it with the porters.
Welcome lunch? Eh, I don't need it.
We just use the free meals available, so a coupon for % off dining offers doesn't help. *IF* I knew we were going to specialty dining, MAYBE.
Sports activities is a maybe. I know there was dedicated times for Florider for Key holders, don't know about other activities.
Spa services... $60 off a $250 spend... do I plan on spending $250 in the spa?
"Fast Lane" access? Haven't needed it, same with priority departure & dedicated seating.
I don't do internet on cruises so that doesn't help.
If I need breakfast on departure day, I get up early for it.
For ME, it's not worth it. Do you plan on spa purchases? Will you use specialty dining? Will you be getting internet? Price all those out and compare them with and without the Key.