Heck, 55mm is great if you want to mimic lots of traditional photographic filters. It won't actually replace some filters for shoots (ND and ND grads I feel should be on the front of the lens) but with most others it does a gosh darn fine job. Nattress' filters are superb. I have the full set and use them often. He does a great job of updates, too--always striving to make things even better with an almost fanatical attention to improvement.
Chet
Las Vegas