My polarizing filter has been on my camera for most of summer and it does a great job, although I have noticed the general exposure is often appears a little under exposed on some foreground detail, It is well know to photographers that such filters do a great job making the sky more interesting, specifically making clouds look whiter and giving depth to the sky. This is well know and discussed often and probably the main reason given to use a polarizing filter. However there is an even more amazing feature that filtering polarizing light.can fix. That is cutting the glare reflected on the surface of water. This glare is strong polarized itself by the reflection from the flat surface of the water,and crossing the polarizing filter normal (ie at 90°) to this actually cut the glare so you can see into the water.
On my polarizing filter their is a small triangle ∆ etched into the rim of the filter, That marks the direction of the polarizing filter alignment. So I can reference this to see when it is vertical (Ie on top of the lens), Or rotated to horizontal (ie point to the right or left side of the lens). You can also see the effects are fairly dramatically through the view finder.