Spoilers abound.
I highly doubt the modding tools can fix the game. I just completed it, and it was really really bad. I am not sure what the general consensus on the codex was, but god : the interface was awful, it is a console game at heart and full of bullshits. Alchemy and Crafting were perfectly useless. Character development was weird and fucked up. The combat, my god, do not get me started on the combat : it mainly involves rolling around and once in a while do a sword blow or most often in my case throw fireballs. Once you're out of mana, it's just rolling around until the mana regens and you can cast some more fireballs. Difficulty is ridiculous : 99% of the combat are so easy you cannot lose, the last 1% is almost impossible. That kraken creature fight was based solely on randomness. Sometimes, you are attacked at thend of a cutscene by guards with bows : they start shooting before you get control of your character again and you start with 10% of your life if you just have shit luck at the moment.
The story is also incredibly badly written and confusing. Seriously, I have not read the books and it was possibly my mistake but CD Projekt said at multiple times this wasn't necessary. I followed Witcher I's story perfectly ; the sequel let me play in a perpetual state of confusion at what was going on around me. Internal politics of the game world are crazy and people talk from the start like everything they said is pretty obvious although it is the first time you are introduced to such concepts and notions. Some key scenes are hidden and just told by Dandelion or other characters in an even more confusing way. The developpers also failed to make you care about what happens to the world around you and concerning Geralt's story, the storytelling is also awful. His story is never mentioned, except in hastily done prerendered cutscenes which explain his matter-of-the-fact without explaining anything. Geralt died and ressurected ? It appears to be no big deal to him. I'm supposed to care about Yennifer ? Who the fuck is she ? It also has inconsistencies. The incredibly lengthy dialog with Letho at the end where the bad guy needs to explain everything that has been going on is also the mark of a bad storytelling. There was even an inconsistency with this one, where it is said that Letho went after Foltest after killing Demavend. Really, then what about Witcher I ending ? No question about that Geralt ? Fuck you. And what about those bits that let you control other characters ? Nobody told CD Projekt the whole world recognized this as a bad idea too ? Interface gets awkward, people talk about more shit you can't understand ; I also loved the Assassin's bit where the wolf traps suddenly get deadly where as it doesn't hurt Geralt for shit. You have to avoid the brown traps hidden on a grey background with a stupid fuck instagram filter. Get hit once, try again. Where's Waldo ?
The sidesquests might make up for it then. Well, no, there are no sidequests. Actually, only a couple by chapter, all not interesting at all. Kill monsters, win at dice, win at arm wrestling, seriously? Is this what we have come to ?
It's a pretty game, though, I grant you that.