I was having a look at this issue and the IS250 got only 2/5 stars; usually What Car? had given it 3/5.
In comparison, its competitor the 3-Series is nominated 3 times in their Compact Exec category and wins it!
http://www.whatcar.com/car-news/what-car-car-of-the-year-awards-2011/compact-executive-contenders/254786
http://www.whatcar.com/car-news/what-car-car-of-the-year-awards-2011/compact-executive-winner/254786
I, patiently, wait the 3rd generation IS, and hope it really gives the Germans something to think about!
Of course, it's just WC's opinion - they'll be lots of people of this forum who have driven the 3-series and still prefer the IS so it's down to personal choice.