Pros:
- If you like seasons, you get them.
- Excellent beer. Many bars. Great nitelife.
- Clean. No poop on the streets, even in the worse parts of the city.
- Great public transportation (except Milwaukee).
- Cheap rent (2BR for $1500 along the river with a view of the skyline)
- Many excellent CS departments in-state and in the states surrounding. (UW-Madison, UIUC, UMN)
Cons:
- Tech scene is slowly simmering. Madison's is growing like a weed, but elsewhere it's quite slow.
- Not as much outdoorsey stuff to do as in the Pacific Northwest, but there's still enough to do (skiing, fishing, hiking, biking, etc. -- just not on 14kfoot mountains)