I'm new to the forums here, and have been wrestling with a similar dilemma. Let me say first off that I'm one of those dedicated manual guys. I like it, because I'm used to it I guess. And it's a lot of fun to row up and down the gears. Plus, in the winter on the snow being able to modulate the clutch and the gas is a big advantage. Almost as big as AWD - I've just never felt as comfortable driving in the snow in an Auto (then again, I should qualify by saying I've never tried paddle shifters either).
But to digress, I love the IS 250, but have also heard that it's just not the performer that some of the price-wise competition is. Namely the WRX (which in Canada clears the $35 000 CND mark along with the IS), the Mazda Speed 3 and 6, the Honda Accord V6, etc etc. As people here have already said, the Lexus is about luxury, class, style, with a little sport thrown in. And that's what's making me look favorably in this direction. I'm not a stop light racer, and I don't intend on taking a luxury sports sedan to the track, so I'm not entirely sure that the extra 2 seconds or so to 60 mph is worth the extra cash that a 350 requires. And, as above I really like the traditional manual.