I've been playing this on both my rigs. Yeah the game is buggy. Smooth flowing is not something that really applies anywhere for more than a few seconds here and there. I do recommend it be installed in a SSD. I tried it on SATA III RAID0 platter raids on both rigs and when I put it on an SSD I saw a pretty big change in load times and also all the annoying pauses between cutscene transitions were greatly minimized. They're still there but at least now it feels more like a dropped frame or two as opposed to feeling like something just crashed.
Old Rig: 2600k(4.2ghz), 16GB(1333mhz), Z68, 2xG1970's SLI, 1440p, 144hz G-Sync
New Rig 4930k(4.1ghz), 32GB(2133mhz), X79, 2xXteme1080's SLI, 4k 60hz V-Sync
The Old rig @ 1440p: All textures/shadows maxed, FXAA and G-Sync(all V-sync off) avg's 40-80fps. Uses roughly 6-10GB Ram, stays pinged in 3.5GB Vram limit of the 970, and according to MSI afterburner its using a pagefile around 10-20GB's. The 970's stay fairly cool in the 60-70c. CPU usage averages 40-50%. It's obvious the game wants more Vram than the 3.5gb the 970's give but otherwise very enjoyable thanks to G-sync.
New rig @ 4k/60hz: Everything maxed. V-Sync On. It averages 50-60fps most of the time and dips ~40-45fps. Will use ~10-16GB ram with Vram mostly around 6-7GB and sometimes a little higher. Afterburner's report of pagefile is the same 10-20GB. This game makes my 1080's run HOT. I've never seen this in any of the other demanding games I own. They will average 70-80c and only on this game at this time. Witcher3/GTA V/Fallout 4/Doom don't do this, they all hang around 60-70c. CPU usage is around 35-45%. The game recognized and enabled HDR10 for the HiSense 4k HDR TV I have connected. I didn't have to do anything other than leave it on auto. Pretty cool on that front.
Play experience is nearly identical between both rigs now other than resolution. Both rigs originally had the same RAID0 platter setup(2 Seagate 500GB SATA III) but now the 2600k rig has a Toshiba OCZ 960GB. I can't emphasize enough how an SSD can make a difference for this game. An SSD won't cure this game's bugs but it will make them less painful.