The more I think about the ending, the more confident I am that I like it. I like it a lot, in fact. Not so much the final conversation, in which I thought the seams were a little too visible, but the part on the island.
I understand the complaints about the Deserter undermining the police work you did leading up to the finale, and I have complaints of my own regarding how you get there. The thing is, the entire investigation has already been undermined before that, by the tribunal. I said earlier in the thread that the tribunal was when I stopped trying to fit the wacky extremist character I had envisioned into the game, and realised that the thing I most wanted to do was to prevent the deaths of Titus and the Hardie boys, "roleplaying" be damned. I failed to protect them, and although it's clear in retrospect that there's no way to prevent a bloodbath, at the time it felt like my fault for not having been dilligent enough in my investigation, or for saying the wrong things to the mercenaries. The tribunal, I think, is the real catharsis of the story, and it *has* to be a failure for the whole thing to work. I ended up telling them Klaasje was the culprit, more out of desperation than because I really believed it. Would they have believed me if I had arrested her? Should I have? Could all this have been avoided if I had just kept my gun holstered and my tongue straight? The game has shown enough C&C at this point to convince you that these questions are legitimate. You're supposed to feel as though you could've done more, and I for one felt pretty bad about the way things turned out, even though I got close to the optimal outcome. To make this convincing, the illusion of choice is absolutely essential.
Then you go to the island, out of obligation to your station or to Kim, or determination to see the case through even though it feels like you missed your window. You find a broken old man who acted on an irrational vendetta and doesn't know or care what he has set in motion, and you realise the whole cascade of events culminating in the shootout was utterly needless. Flap of a butterfly's wings and all that. The discovery that there wasn't a mastermind behind it all, but rather just a random loony Gavrilo Princip at the wrong place at the right time, really hammers home the tragedy of the thing, as well as Klaasje's torment and Ruby's death (if you fail to save her) in a way that wouldn't be possible if you had gotten to Sherlock Holmes your way to the killer. Essentially it changes the course of the plot from a whodunnit to a tragedy.