Against my better judgment, I broke down and bought the DLC last night instead of waiting for a patch or two. At least I didn't preorder it, but it still sends a message to Paradox that I'll buy stuff on the first day even if they haven't put it through serious QA...
Despite my fears I didn't run into any bugs though. Supposedly, robot job prioritization is very broken right now, but I'd only just unlocked the tech when I had to quit so I didn't get to experience that. I didn't have any problems launching the game like a few people have reported either.
I didn't really get much chance to see the new features though due to a bad start. I had a single dig site in my borders, where my neighbors all had 2-4 in theirs, and one even had a relic world. You can only perform archaeology digs in sites within your borders, which makes sense I guess. The one dig site I got to play around with was kind of cool, but in the end the archaeology system works more or less like I expected: it's special projects with multiple steps that just take a random amount of time to complete now. I like that there's a little more interactivity there now and that it has the potential to keep the discovery phase of the game going past the early game, but I got unlucky so I exhausted it all within 20 game years.
I also didn't get a chance to use any minor artifacts. I picked up one from that dig site, if I remember right, and maybe a dozen from the Irassian precursor event chain, but never could figure out how to do anything with them. I believe you have to research one or more technologies to make use of them, but I didn't get any of the tech cards by 2230. I expected there to be an indicator somewhere of how many you had though, which I couldn't find. Maybe that only shows up once you research the techs.