[markgozz]

Square vs round , personal I would go for the square type you may only have the one kit lens at the moment but as your kit grows you will be able to use the square filters on all your lenses just by changing the adapter ring ( About £7 each ).

If you are interested in long exposure photography then I would suggest splashing the cash on a good quality 10 stopper ND filter , you can stack lower ND's but you then run the risk of introducing a colour cast into your shots . You will probably also need a set of ND grad filters to even out the exposure but you can pick up grad kits with three or four different strength filters for under £ 50 .

If you are after a starting point to see how you get on with filters then I would suggest the square grad kit , any colour cast caused by stacking the filters in front of each other can be sorted out if you shoot in RAW and they are also very handy in normal landscape photography to stop the sky from being over exposed .

Mark