I love my tickler file... Have used it for years, and it's paper. But that's just me, and as everyone has said, it's a purely personal decision - as is every other facet of your GTD system.
I LOOOVE getting mail, even junk mail (probably fodder for a psychoanalyst) so the tickler file is like getting mail every day! Even if it's a bit of humour or something I put in there years ago. Still fun to look at. And I love the act of saying "I don't have to deal with this today or even look at it - into the tickler it goes!" ... out of sight, out of mind.
By the way, greeno - love the Albatross reference on your blog. "Of COURSE you don't get wafers with it!" Classic... I'm probably as much about paper as you are about paperless!