Its a fun lens - you'll soon get used to it and the lack of IS. On a related matter its not too early to start thinking about some real camera stabilisation - iow a tripod.So I got my lens, Sigma 28-300 today, at New World, Menlyn. Got it for R3500, best price I got. It was the last one, so dont try to get one at the same price.Also got the Kenko polarise filter there.
I tried a few shots afternoon, I must say I miss the IS a bit. And setting a higher shutter speed maked the shots dark. But I'll learn, I'm still young.And I need to practise with the filter too. There was no sun, was cloudy, so I suppose the polariser won't have an effect. But as I said, got a lot to learn.
Oh and yes, Outdoorphoto's prices on the Kenko filters are the best.
There's no need to keep the filter on unless you need it.
This might give you some helpful info http://www.great-landscape-photography.com/polarizing-filter.html