Got my Ultra 2 eight days ago. For what it's worth, my thoughts:
I'm not an extreme athlete, I just bought it for the bigger display, better battery life. Also, I was drawn to it because the Ultra is the only Apple Watch that doesn't look exactly like every other Apple Watch. I like the rugged styling and the Titanium finish.
Coming from a 2-year-old Series 7, the Ultra's battery life is shockingly great. That said, I didn't mind charging my Series 7 every day, and I never was in a situation where the Series 7 ran out of charge. But still, Ultra battery is fantastic. Very happy.
The bigger screen compared to my Series 7, for me, isn't as much of a benefit as I expected it would be. A couple times I've worn both watches on the same wrist, opened the same app on both, and the Ultra's bigger screen doesn't seem very much larger. This surprised me, because when I moved from Series 6 to Series 7, the larger screen of the 7 made a bigger impact on the quality of my experience.
In side-by-side comparisons with my Series 7, I see absolutely zero speed difference with the Ultra 2. The speed of opening apps, scrolling, or doing many various tasks is virtually identical on the Ultra 2 as the Series 7. Now, I know that the new, more powerful chip in the Series 9 and Ultra 2 has other advantages, like the snap to open feature coming in watchOS 10.1 and on-board Siri operation without an internet connection. But in terms of running most apps, thee's no apparent speed difference, to me.
In bright sunlight, my Series 7 is readable, as is the screen on the Garmin Edge bike computer/GPS I take on my longer rides. But the Ultra's display is much better than both. It is perfect. The readability is outstanding, just as if you were indoors. Of course, the Ultra is designed for outdoor activities, so this exactly what you should expect, and I'm happy that Apple delivered.
The extra weight and bulk of the Ultra compared to the non-Ultra Watches is sometimes a nonissue for me, and other times it's noticeable. For me, sleeping with the Ultra on my wrist is absolutely no problem, no issue.
Lastly, about cellular.
I don't have a compelling need to active cellular, but if it were really just $10/month here in the U.S., I would activate it and live with it for a couple months to learn how I can take advantage of it.
But my carrier, Verizon, charges not only $10/month, but an extra $5.22/month for various taxes and surcharges, and a $35 activation fee. I told Verizon I'd pay them $10/month plus 5.25% tax, which is the sales tax rate in my area. I told them they could either get $120 per year of my money, or they could get $0 of my money, whichever they prefer.
I also told them if they insisted on charging the $35 activation fee and the extra $5.22 in surcharges, I'd start looking for another carrier that would offer me a better deal on the two phones on my account plus a new Apple Watch. The customer service rep I was talking with said something to the effect of, go ahead, we don't care.
That's infuriating, but not surprising. There simply is not much choice in the cellular service market, thanks to mergers and acquisitions. It would be harder for any one cellular company to get away with charging customers ridiculous fees if consumers had more choices, more options.
Rant over.
Overall, the Ultra 2 is impressive. It's overkill for my needs, but I get more than enough benefit & value from it to justify the cost. I'm sure the value I get from it will increase as I explore and learn more about it.