Great location, fantastic views - horrible elevator system.
I stayed At the Swissotel several times this past summer, and all of the stays were great. Nice, quiet rooms, well-appointed. The staff is very attentive and helpful, although at certain peak times the hotel front desk is understaffed for an influx of check-ins or check-outs. It is a fairly busy hotel - plenty of energy humming.
The location couldn't be better: it's within walking distance of the Miracle Mile (to the north) and to Millennium Park and the Museum district to the south. Parking a car is very expensive anywhere in Chicago - it often costs more than the daily cost of the car rental - so I tend to cab it around.
The room service is pretty good, although with a pretty limited wine list available (swing buy Mariano's market and pick up a good bottle on your own). The Palm restaurant located in the hotel is very expensive and sort of old-fashioned; trying to be Sardi's without any charm. Definitely geared for the expense account crowd. There are many much better alternatives nearby. The little chocolate chip cookies available in the hotel gift shop are worth every penny (of which you will pay many) - but you will love them.
Try and get a waterfront room, it is worth the view of the river, Navy Pier and the Lake.The corner rooms facing the water are sublime. I booked my rooms on the Swissotel website...they often have really great internet-only deals available.
The hotel has a huge and nicely-equipped health club on the top floor, incredible views while working out. 
A rant: the elevator system is horrible. It has a centralized input that directs you to an individual elevator. But if the elevator is full, you might not get a new elevator available to your floor for many minutes.There are no buttons inside individual lifts. It works (or rather, doesn't work) the same way descending or ascending. At peak times a trip to your room can take 30 minutes. And - since the hotel has a fair bit of convention business - peak times can be anytime during the day; when a conference let's out fro a break....bam, it's peak time. Walking up 36 floors isn't in my fitness program...but I did think about it more than a few times.
Check out 'Maison Brasserie' and Mariano's market nearby. Also 'The Gage' and 'Henri' restaurants on South Michigan. 'The Goat and the Girl" and 'Gilt' are also cool.
If you can get a good on-line the deal, the Swissotel is an unbeatable value. Even if you don't, the location, facilities, staff and ambiance make for a great stay.