Didn't realize there was a whole community thread here for the series, and not just TW3. I recently replayed through 1 and just began 2 in working my way up to the final game, after being a fan of the books. Guess I'll give thoughts on them and set up where I am. Bit longer than I anticipated, so apologies for the length.
The Witcher
I didn't think much of it back in 2011/2012, but this one is a bit weird coming off the book series. The Wild Hunt stuff in particular is odd, as it's mostly a side show and very much a different beast than what is the books and this game's sequels. It's main story was also this weird blend of aping to the point of repeating events of the books, as well as really being a side piece to the overall arc that the other two games carry through. Can't say I was a fan of some characterizations (Shani, Schoietel path Sigfried) and the sex card aspect, though many of those romances were fun to pursue.
Gameplay-wise, I actually have a bit of a preference to it despite it's rather simple presentation. Pop potions whenever, switch styles and swords for the proper opponents, parrys and such are dice rolled in the background, and just click when prompted to combo. At times it was too simple, particularly when not underleveled, but it beats rolling around and hardly seeing anything. Gauging what to purchase and upgrading was also rather straight forward, even if much of it was superfluous.
This run was opposite of my original. I stuck with Triss, aided the Schoietel, and fought off the King of the Wild Hunt over the soul of Alvin.
The Witcher 2
Im still rather early on, perhaps nearing the end of Chapter 1 where I have to choose to follow Roche or Iorveth to take on Loreto, and I'm still somewhat adjusting. Decided to play on Dark, figuring I'd have a rather easy time once I grasped the gameplay. That's still an ongoing process.
Obviously, the presentation is a major improvement from the first. Characters are now emotive and animate in conversation. Many of the environments so far look great.
That said, that's probably the only major compliment I can give it this early over the first. There's a lot going on in this game, and much of it isn't explained well. Reinforcements and enhancements, Mutagens, attributes, and skill limits have no explanation this early, but are not lacking and shouldn't be ignored. Fewer opportunities to obtain/find formulas and diagrams, putting a heavier emphasis on buying, with the game relying on the abuse of it's gambling system to make money over any contract.
The gameplay is also a bit disappointing. Combat is essentially spamming Quen and rolling around like a mad man until an opening presents itself, slash or two, and repeat. The enemies are quite engaging, but any other tactic leaves the player too open most of the time. There's also an issue where many situations leave the player quite unprepared, as there were few or no indications of what may be needed to tackle a challenge in the way of bombs, potions, and traps, all of which must be prepared and imbibed prior to the beginning of conflict.
Worst of all, are the technical problems. Things disappear and won't load back in despite earlier saves. Dialogue halts and won't continue. Inputs not registering many times. And a multitude of issues related to the save system, which can causes crashes due to no overwrite system in place to curb the save files. There are also odd points where the game doesn't allow manual saves despite there being no combat or other circumstances that would prevent such a thing. The game certainly has that console first port thing going on that it never did grow entirely up from.
I'm probably being rather harsh, given much of the issue was jumping into Dark difficulty for a first run, and that it's still early on. I'm enjoying the story and characters (awful sorceress garb aside), and I'm starting to grasp elements like enhancements in how they are implemented here. Hopefully that upward trend continues through figuring out these systems and the opportunities leveling up may provide.