Man, after playing a lot more of Broken Sword 4 I can safely say it's the worst of the BS games. For the sake of the argument I'll compare and contrast it with BS3.
The controls are the first obvious problem I have with BS4. I know what they were trying to do; they were trying to renovate the classic point & click adventure style, but frankly it fails miserably. The second and most inexcusable flaw I've noticed is the absence of emotion in the characters! The very beginning of the game is pretty dry and you never really notice, but when you see the cinematics you really see how plain and 'unanimated' they are. In comparison to BS3, which had some pretty good action cinematics and cutscenes, BS4 seems entirely animated with the basic character movement animations. BS4 is just completely devoid of any sense of action or drama when it comes to the cinematics, unlike BS3.
BS4 is graphically superior to BS3, but that's about it. In all the previous BS games the puzzles were compelling, coherent, and logical! They actually make you think. In BS4 only a handful of the puzzles make sense, and you they don't just require you to think, you need to completely release yourself of your mental constraints and think outside the limits of common sense. Ok, I might be exaggerating a little, but my point remains that BS4 just doesn't feel like it was as well thought-out as any of its predecessors.
The story seems alright so far, so that's the only reason I'm still playing it. I haven't finished it yet, but when I do I'll give my final "set in stone" decision on it.