Interestingly I am working on a TPP camera script too. First of all I prefer a TPP cam that always follows the player, but that's just personal preference.
I see you warp the camera on sight obstruction trough the geometry. This may lead to more obvious clipping artefacts with textures and low framerates. The alternative, a jump-cut, may be clipping-wise saver, but it's also pretty abrupt. It is a dilemma of these systems, but is game geometry really so ehrm - obstructive? How often do we walk behind a row of pillars?
I would also smooth the positioning of the camera based on mouse movementX, but again, just personal preference. I've got a smoothing parameter in mine, allowing rigid 1:1 translation, up to a lag that feels like a camera man is trying to catch up with a runaway... "hey, not so fast!"!
All in all good job, pro quality. The warping is ok in a fast paced game. But one day one of us will implement a-star pathfinding so the camera can physically correct circumvent phong-shaded cubes :)