Hoya 77 mm Circular Polarizer Filter

I bought this filter for my Canon EF-S 10-22mm, just before going on a vacation and have used it extensively for about 20 days and as expected I am very satisfied with the increased color saturation and decrease reflections.

Here are my observations:

1)Observed slight vignetting when used directly on the lens at 10mm.It's a shadow like vignette(sometimes depending on ambient light,it's not noticeable at all) and you can still get details out of the vignette with a photo editing software.

Effective thickness of the filter after screwing it on is 8mm.
i.e.,protrudes 8mm out of the lens.

2)Canon 77mm Lens Cap fits perfectly over the filter.
Be cautious while removing the lens cap as it pulls on the outer glass if u try to remove it with out pressing the clips .
I read some reviews where people said the outer glass just dropped while they were using the filter and I suspect this could be the reason.
With proper care I don't see that happening.

3)Well built,feels durable,the outer glass rotates smoothly.

4)Easy to screw on and off the lens without any hassle.

5)Good quality glass. I didn't see any reduction in sharpness in the image with the filter on, with 100% zoom.

6)Easy to clean with a lens pen.

7)Flares.I have read there are some expensive filters which reduce flares more effectively.

To summarize, I am very satisfied with the built and optical quality of the filter and until it lasts I don't feel the need of buying an expensive filter(Hoya HD, B+W, etc).

For the cost to value ratio it deserves a 5 star.

Flipkart delivery is as good as always.

Many people don't understand polarizing light, so they expect more from these filters than they can deliver. Polarizing filters depend upon the angle of the light essentially being at right angles to the axis of the camera lens. When used with a very wide angle lens, the likelihood of that light being at a uniform angle to the axis is about nil. As a result, when you look through the viewfinder, and rotate the filter, you should expect to see non-uniform darkening of the sky, when used with a wide angle lens. However, once the light hits trees, fields etc., it is scattered -- so the inconsistency of polarizing effect is much less pronounced. The issue is solely in sky. You may be able to reduce that effect by shooting at a different angle to the source of light (sun) - but that probably won't include the scene. Even if you fix the aperture and shutter speed, you can't shoot multi-image panoramas with a polarizing filter.

My biggest worry with this filter was Vignetting on my Sigma 10-20mm lens. Received this filter the very next day after placing the order. I must commend Flipkart for their service.
Good news is there is no Vignetting at 10mm with this filter. A big relief I must say, otherwise I would have had to compromise shooting at 10mm.
My next test was to stack one more filter (ND i.e) with this one. There is good amount of vignetting at 10mm on the corners, but it disappears at 11.5mm and beyond.
Quality of polarization is not as good as Hoya's PRO 1D series, but it is good enough for amateur and a bit of serious work.