A problem with the polarizer is that it can cause an uneven darkening of the sky, you get very dark blue on one side of the image and a much lighter blue on the other. However I would not write off the polarizer, it can give some much needed sparkle to a scene, just use it with care.

The effect of using a polarizing filter is entirely dependent upon the relative positions of the sun and the camera. In some situations it has very little affect upon the appearance of the scene.

You don't need to buy a "circular" polarizer for use with film, although if you use it with both digital and film cameras the more expensive circular type will be necessary.