Almost level 20 now and have greater blue and green mutagens, with blue set up with maxed Igni, Yrden, and switch the 3rd between level 1 Quen and level 2 Delusion. I finally got enough lesser red mutagens to make a red mutagen with maxed Fast Attack, Level 4 Strong Attack, and level 2 Resolve. I still need to get 6 more lesser red mutagens before I can craft a greater red. I'm told you need to be level 20-25 to farm lesser red mutagens, and I'm about 270 XP away from level 20, so I'm currently stalking a Fiend contract in hopes to get another lesser red. On Green I have a greater, but only have one matching category skill under it, Heightened Tolerance, at level 3. I also have level 1 Survival Instinct and Devastating Blows in that tree. When the 4th tree unlock, I'll be moving the General category skills over to it, and probably add Poisoned Blades and Frenzy to the Alchemy tree.
I'm still playing with alternate movement response, but it's really only faster, with the same sloppiness. For some reason I get less random sign selection changing now, though it still happens now and then. Maybe it's just that I've gotten in the habit of always checking it before battles. I'm getting much better at dodging and striking from behind with harder enemies like the shield guys, but the combat often feels clunky and AI very dumb. If you so much as do a couple rolls, they will be standing right near you at 3/4 angle and not even see you. Plus I still get the odd stuck in a certain pose or without weapon drawn problem now and then.
I've also found the Bestiary often isn't really worth a damn, or even most wiki sources, because they mostly go by the Bestiary. The game will even tell you in the detailed info about Higher Vampires, that they're invulnerable to fire. Yet the Bestiary says to use Igni on them. The best way I've found to deal with creatures is to either experiment to see what works best, or chat with those whom know the game well. Golems are another prime example. The Bestiary and many wikis will lead you to believe they are pretty much invulnerable to signs, listing none, yet I've found that ALt mode level 3 Yrden not only distracts them, it damages them quite a bit, and if you circle around behind them with max Igni, you don't really even have to damage your blade.
Creatively the game is beyond expectations though, with the depth of even minor quests, the vastness and variety of the game world, and the sheer number of creatures, which also vary quite a bit in how they attack. It certainly has it's quirks, but many of them I'm figuring out how to minimize or deal with. Like simply selling goods for instance. Often times the item highlighted is not the one sold, but I've found you have to wait for the info of the highlighted item to pop up before you can be sure it's the one that's going to sell. The inventory menu is a bit sluggish that way.
I don't know if I'd call it GotY, especially since it's so buggy over a year after launch, but clearly it's better than I thought it would be.