[OnePlus 10 Pro] yo-less:
It was GSI-like 😄. I've had quite some experience experimenting with GSI ROMs and there is just one big problem: If you're running a GSI-phone you have to accept that some of the phone's features will never work. I mostly tried to flash it because I spent more than 1000 € on the phone and the wireless charger and they've both been sitting here for months while I'm still using my Mi 8 Pro, because I refuse to run a phone on Spyware OS. I'm really bummed out that this is the second time this has happened to me, because it was the same with the Mi 8 Pro, only this time I had checked out the ROM development on the other OnePlus phones up till now when I made the purchase. I will NEVER buy another OnePlus phone and I will also never again buy a phone on launch. It's not like I really need a phone the day it is released anyway.

Concerning your question: The experience itself was good. Everything that did work worked really well, it was a snappy experience and to be honest, there's not that much of a difference between different ROMs anyway, people seem to be pretty religious about the differences between ColorOS and OxygenOS, but in the end, it's all Android in different flavors. Flashing took almost no time at all, you just have to make sure you follow the guide here by the letter. I had updated the phone to NE2213_11_A.16 before I started my GSI experiments, because that was the latest version on Oxygen Updater, so I could make sure I'd end up with right stock zip to go back to.

It's just that when you start using the new ROM you realize right away that the fingerprint sensor doesn't work, face unlock won't work and all the other typical problems with GSI ROMs (I don't have a SIM card in my phone yet, but I'm sure VoLTE won't work either, it also didn't work on my Mi 8 Pro, but I can live without that). And I've come to accept that the Mi 8 Pro I'm using will never be fully functional, but I've spent so much money on the OnePlus 10 that I'm not there yet. There's always threads claming you just have to flash this zip file or that zip file or replace this or do that but in the end nothing ever worked out for me. I'm not an Android developer, but my experience has been that the features that don't work on the first boot-up will never work. I also noticed that the camera app that comes with the dotOS GSI ROM isn't as great as the stock camera app on the OnePlus 10 Pro (Even though I'm not really all that impressed with the photos the OnePlus 10 Pro takes, I do have an excellent Sony camera for photos, though, so I'll never be too happy with smartphone photos, but I feel that the OnePlus 10 camera app filters the **** out of its photos and in the end, the result always seems a bit unnatural to me either way.

Also, it took me weeks of experimenting with the GSI ROM I've installed on my Xiaomi phone until I had everything set up so I could live with it (and I've been using it this way for over two years now). I have a GCam mod apk that I use for photos, but it freezes when I try to use it for video and so on... . I'm not ready yet to fiddle around with the phone for weeks until everything is more or less acceptable. And I really want to start using the fingerprint sensor, I have several apps that require passwords and it's just so much of a hassle to always type everthing in. So I'm still hoping for some custom development for the OnePlus 10 Pro, but I'm a bit pessimistic at this stage, as nothing seems to be worked on at the moment. There was this one post here some weeks ago, but it doesn't exactly look like anyone is actively working on it, the last commit was made 15 days ago.

I want to try out Kaleidoscope OS as well, just because it looks interesting, but the truth of the matter is: If you choose to go the GSI way, you have to settle for less and you have to spend a lot of time figuring out what works and what doesn't and how you can arrange yourself with the resulting restrictions (Fun fact: On my Mi 8 Pro, I can only get text messages in some countries when changing the network from 4G to 3G, it seems to have to do with some IMS problem? Also never found a fix for it, even though there are quite a few posts claiming to have found a solution).

Also, I tend to spend a lot of time setting up my apps, transferring data and so on, so I really want to have a ROM that generally works well so I don't have to do it again and again every four weeks.