Average experience
I was disappointed by the Hyatt Regency on Wacker. My husband and I stayed there for five days on a recent work trip. 
I was immediately annoyed to discover that there were only THREE drawers in my room. Very irritating when you're staying there for an entire work week--I would have liked to be able to take out all my clothes and put them away (which I had planned on doing). It was annoying to live out of my suitcase all week, particularly when I was there working and attending receptions--situations where you want to look presentable, not creased and wrinkled.
The bathroom was TINY. Our stuff was always spilling off the little counter. 
Additionally, there was no refrigerator in the room. We had planned to buy some breakfast foods and other snacks to nibble on (and cut the costs of buying food in the city for the week). We called and had a refrigerator delivered. Maybe it's our fault for just ASSUMING they weren't going to squeeze every last dime out of us, but when we received our bill we found that we were charged $25 a night for the refrigerator! It would have been nice to know that was going to happen, because had we known we would not have asked for the fridge. Frankly I don't think it's my responsibility to have to ask, "Wait, are you going to charge me for this? Can I use the shampoo? Is that still free, or is going to run me $10?" (We did complain and were told the $100 would be deducted from our bill, but it's been a week and that has not happened, so I'm going to have to call and haggle with them again.).
Another complaint is the high cost of Internet access. I know, I know--they charge you for Internet access. I get it. But it's just RIDICULOUS. I think the Hyatt was charging $12 (or maybe $15) a day--and for some reason it was even more in the business center downstairs (I'm pretty sure I was told it was $7 every 15 minutes. Agh! That is INSANE.) So many of the people at that hotel are there on business, obviously working, attending conferences, etc. and it really left a bad taste in my mouth that we paid to stay there for a week and still couldn't log onto the Internet to work without paying what I think is an exorbitant fee. 
In somewhat positive reviews, the "Big Bar" was fine and the prices were about what I'd expect in Chicago. I had expected it to be *awesome* because I had heard that it was, well, awesome. I didn't think it was AWESOME, but it was okay. I wouldn't purposely go there unless I was staying IN that hotel. I will say the waitresses were REALLY nice and very responsive, which was nice. 
Also, I thought the location was pretty good. I liked that I could easily walk to lots of restaurants and bars on and around Michigan Avenue, off Wacker, etc., but the hotel was also close to LSD so we could easily hop on and drive up to Lincoln Park for dinner. 
Finally, a mixed review on the bed--I found it very comfortable but my husband said he could "feel every spring." For context, I am usually comfortable unless the bed is super hard, and I thought it was soft and springy. If that's not your thing, you may have sleeping issues.