I've got a IS 200 Sport and currently have an IS 300 (SE or Sport the usual tell-tale signs are confusing?) from Lexus while mine is in for warranty work. Long and short of it all is I really want one now, at first I thought I'd hate the auto box, but its bloody nice, I thought there would not be much performance difference, but it is really apparent! My only gripe is it seems to drink a lot more fuel than my 200, but as I was saying to Mike the other day It could be because I'm not used to the Auto box.
Go for it, I'm thinking about it!