Mostly because a lot of people saying "Oh my gosh, it's like Nale, but AWESOME!" to the point that I'm starting to get tired of it.
And I guess I should make my position clearer: I like OotS. I like the writing. I like the way that Tarquin has been dealt with SO FAR. My only problem is that, the more I'm looking at him, the less I can see any real way that he can be "beaten".
Take Xykon and Redcloak, for example. Xykon gets defeated when his soul gets destroyed along with his body. Fair enough. Redcloak? Get past his fancy god-connection, and he's only flesh and blood. Kubota? Thwart his plans, then deny him the trial that would most likely get him off (granted, I see that as V going too far, but never mind). Miko? Show her that she isn't as all-righteous as she claims to be. Each of the other characters that have been described as "evil" or "hindering the party" have some sort of "If this button gets pressed, I lose" thing, even if that button requires 50 zillion steps to unlock.
But for Tarquin, he doesn't seem to have an "I lose" condition. From the plan he detailed to Elan, he seems to have planned for everything. He's essentially the "perfect" bad guy, and that just rubs me the wrong way.
So. Too long didn't read version: I like Tarquin as a character. But I don't like that he seems to have no weaknesses.