A new Hyatt waiting for a makeover!
Hyatt recently acquired this property from Wyndham so this initial review may be subject to change in a couple months as they get "used" to being a Hyatt. 
The first word that comes to mind when describing this property is DATED. It is is desperate need of an overhaul from beds, to decor, to TVs (25inch boob-tubes, really?), to everything. The rooms are spacious but the carpet, paint, and furniture is about 15 years (or more) out of place.
Perhaps the transition to Hyatt has not gone well. I never saw a staff member smile. Sure, they said "Hello," "please," "sir," and "have a nice day," but never with the sincerity that I have come to know and love from Hyatt (which is bizarrely strange considering Hyatt's headquarters is a 15 min walk away). 
The rates were low (less than $125) for a king and included breakfast but I had to nudge them to issue the breakfast vouchers. There is ONLY valet at $54/night (ouch) so maybe you might want to skip the car or look at a nearby garage. Internet is NOT free and goes for $10.95/night. If you are a member of goldpassport (platinum or diamond, it is free but they did not automatically remove it - so double check your bill). Business center and fitness center were just ok.
I did have breakfast, which was okay. Nothing to get excited about it. Skip the buffet and have them make you a fresh plate. Again, no smiles or energy (and this was at 9am). I know that they offer some steak dinner special but with the myriad of other places to eat in the area, I would pass for now. Maybe in a few months, after they have been a Hyatt for a while, I would reconsider.
It is in a good location, a block off Michigan Avenue. There are lots of places to eat and drink in Streeterville or cross Mag Mile to the Gold Coast. Its a bit of a walk from the L but plenty of express buses nearby. 
Would I return to this property? Sure... as long as rates were below $150/night with its current refurbishment. Should they throw some money into its interior and/or increase the level of sincere service, only then would it be worth more. For now, though, it is a good place to drop your bags and sleep but not a destination of its own.