Akka: I've avoided spoilers (because I prefer to find things in the games), so I may end up wrong, but from a strictly "played the game" perspective, I have to say that some judgement on Triss are quite harsh.
She is holding things from Geralt, sure. And in her "work", she deceive and manipulate.
But it doesn't mean that she doesn't really care for Geralt. She always took the path that stand by him, and always took risks for him.
The thing is, it's not because she love Geralt that it means she doesn't have her secrets, and it doesn't necessarily means she's betraying him. It seems lots of people tend to have a far too much protagonist-centered morality and exclusive loyalties.
I know that I held up lots of information for myself, without telling some people, and without meaning that I attempted to betray them. I know that I purposedly didn't take part in some battle because I liked both sides of the fight and had a "divided loyalties" problem.
Though it seems it's okay if Geralt does it, and it's a major sin if Triss has the same problem ? Doesn't compute !
Sure, she may have held a bit too much, but I see it, again, as someone torn between two competing loyalties, and having some higher goals, rather than just being a cheating bitch. And you can call on her about this anyway, and her answers felt rather satisfactory. For a game much more realistic in its depiction of events than most, I find it refreshing that it's not all protagonist-centered, and that the morality of people aren't entirely dependent on how they treat the hero.
The problem (and this is not new it has been around since forever) is that most players demand to be a centre of attention (something that BioWare games constantly encourage as well).
There is nothing wrong with a protagonist being a part of a living, breathing world and not an absolute centre of it.