The two opinions are here.

The most interesting aspect of the Illinois Supreme Court’s decision is the disagreement between the majority opinion and the two concurring Justices. The majority paints the lower court opinion as having ignored controlling precedent on the meaning of the term “residency.” The concurring Justices say that the cases before this one have been conflicting, and that both sides had reasonable arguments to make. The concurring Justices seem most concerned about the tone of the majority opinion, which they say reinforces popular belief that the lower court was motivated by something besides law—apparently political considerations.
If the concurring Justices had their way, the opinion would have been just a few pages of analysis, and based on the simple principle that if someone was once a resident, he does not lose his status as a resident by rending out his permanent abode.