IS200/300 great looking car, sporty chassis, drives really well. IS200 auto is sluggish though in its standard form.
IS250 imho - ugly, lumpy, terrible handling, heavy, dull, boring. Never driven an IS350 so cant comment on that.
personally I think the IS250 is not a natural progression from an IS200, theyre like chalk and cheese and not an improvement. You can see in the IS200 some sporting pedigree and a real desire to create a proper drivers' car.
not so with the IS250. it has air conditioned seats, who the hell needs rubbish like that.....