Unfortunately, I have played Gothic 3. It broke my heart. As an avid fan of the first two games, I was really excited about the third entry in the series. Unfortunately, they fucked up just about everything that was good about Gothic.
The combat system was completely broken. Attack animations were too slow so NPCs would miss 90% of their attacks. It was truly sad that it would take about five minutes for a high-level NPC to kill a Scavenger. Conversely, enemies could be dispatched by simply spamming the quick or medium attack. When I was able to kill a whole camp full of orcs (a fearsome enemy in the first two games) at the very start of the game, I was in shock. In addition, the per-pixel hit detection of the weapons meant that it was hard to avoid hitting friendly or neutral NPCs in crowded combat situations and they'd attack you for doing so, forcing you to beat them up.
AI was equally horrible. Enemies would stand still as you pelted them with arrows from afar. Their detection radius was extremely limited so this was a common occurrence. NPC AI also seemed to have forgotten how to jump. In the first two games, if you climbed on top of a platform, the AI would actually jump up and climb after you. Non-combat AI had some gaping logic holes. You could walk into an Mercenary base wearing Rebel armor and nobody would care.
Sound, a really key part of the previous games, was barely existent in Gothic 3. Monsters and creatures were mostly silent and lacked the distinctive warning noises that they had in the first two games. Combat SFX were very limited as well and there wasn't even a SFX for pulling out your sword. Ambient SFX were missing all over the place, like with the waterfalls. The music was great but it seems like their entire budget went into that alone. Oh, they also got rid of all the original voice actors which was a really bad move, considering the key characters had prominent roles throughout the first two games and players had grown used to their voices.
Hell, from a design standpoint alone the game was terribly flawed. Whereas the first two games kept the world small but focused, Gothic 3 tried to convey a far larger world, resulting in lots of small towns with forgettable characters and minimal dialogue. It was clear that Piranha Bytes was trying to compete with Oblivion in terms of scope and in doing so, they replicated many of Oblivion's failings.
And then you have all the technical issues. The game runs like crap regardless of your rig. There are blatant graphical issues (like the broken ocean rendering) all over the place. Then there are the broken quests and skills.
You'll have to forgive me for my little rant but I was genuinely offended by Gothic 3. What was once a great series was raped, bludgeoned and buried. Gothic 3 surpassed even DX:IW as the greatest travesty in sequel history. DX:IW, taken as a standalone game and not as the sequel to the best game ever, was tolerable and in some ways even decent. Gothic 3? I couldn't even finish the game. Just too damn depressing.