I bought the Smart Lock Ultra a few weeks ago.
The Ultra doesn't go on top of your existing cylinder like the older Nuki models. It comes with its own cylinder, made by m&c (Dutch, SKG*** rated). You can adjust the length, so you don't need to measure your door or order a specific
size. I set it to the same length as my old one and installed everything in less than 20 minutes. No drilling, no locksmith. My old cylinder was a Lince, so for me this was also a security upgrade and not only a smart lock.
The keys are the annoying part. The profile is patented, so a normal hardware store cannot copy it. You order the copies online with your security card, and they cost 28€ each.
I ordered 3 and paid 84€. Keep that in mind if several
people live in the house. They arrived in 3 days, which is ok, but order them when you buy the lock and not later.
I use it with the Android app and also from Home Assistant with Matter over Thread, so everything stays local. No cloud, no bridge. Auto unlock when I get home is what I use the most.
Battery: installed on 24 July, it has gone down 7% in 3 weeks. At that rate it should last around 6 months, but 3 weeks is not enough to be sure.
It is expensive, and the 28€ keys don't help. But you are also paying for the cylinder, which on its own is not cheap. For me it was worth it. If you only want to open a door from your phone, there are cheaper options.