I have a galley kitchen with a tile floor that picks up every dropped crumb and every shoe-print of dried-out rain. I have run a mop across it every couple of days for years. The S8 Pro Ultra is the first robot I have owned that did the job well enough that I stopped reaching for the mop on the way to bed. The vibrating scrub plate on the mop module makes a real, audible difference; you can hear the pads working in a way you can't on a robot that just drags wet cloth.
The dock is the part you pay for. It empties the dustbin into a 2.5-liter bag, washes the mop pads in warm water, dries them so they don't grow anything interesting between runs, refills the clean tank, and even runs a self-clean cycle on the dock's own basin. I refilled the clean tank every couple of weeks and changed the bag at the two-month mark. The actual user experience is loading a coffee filter once in a while.
Navigation is the other quiet strength. The LiDAR mapped my two-floor downstairs in about four minutes, and the no-camera obstacle avoidance (structured light plus infrared) caught a phone charger I'd dropped and a dog toy without trying to eat either. If you don't want a camera-equipped robot wandering your house, this is one of the few flagships that doesn't include one.
The weak spot is the part the spec sheet hides. On carpet, the S8 cleans well but not better than the older S7 MaxV Ultra it replaced in my house. The suction reads as 6,000 Pa on the box and measures somewhere south of that in independent tests, which lines up with what I see — it leaves a little more behind on the bedroom rug than the older Roborock did. If your home is mostly carpet, the upgrade math is unfavorable and you should look at the Roomba j7+ or a corded vacuum instead.
Crevice pickup is also weaker than I expected for the money. Along the edge of the tile-to-wood transition I still see a thin line of crumbs the robot leaves behind. It's the kind of thing a stick vacuum clears in one pass and that this machine, despite the price, doesn't quite touch. After six weeks I started running the cordless along the edges once a week as a finishing pass, which feels like an admission of defeat but takes ninety seconds.
Battery is fine. Roborock rates it 180 minutes and I see closer to a real 150 in mopping mode with the suction up, which still covers about 1,200 square feet without needing to recharge. The dock is huge, bigger than I'd want in a small apartment, and the bag refills cost real money over time. None of this is unique to Roborock; it's the price of admission for the category.
Verdict: Buy this if your floors are mostly hard, your kitchen sees real cooking, and you want a robot that mops properly. If your home is mostly carpet, get a Roomba j7+ or save the difference.