I have no idea what architecture critics say about IDS, but I DO know the locals love it.  The main reason is that it accurately reflects the sky.  We live in a VERY active weather zone and the changing sky is an aesthetic highlight around here.  It's central court is still a model of a well-designed public space.  And there are hundreds of offices with spectacular views.  This is the kind of building folks will lie down in front of bulldozers to save.

Tellingly, Pelli designed his building to be just a bit shorter out of respect for Johnson's masterpiece.  In a profession known for its arrogant prima donnas, this was a VERY classy move.

"Remember the I35W bridge--who needs terrorists when there are Republicans"