The worst! Forced to sleep in a closet (no beds and windows)
My wife and I recently stayed here for a half business/leisure trip to Jacksonville. What was supposed to be a pleasant visit ended up becoming a catastrophe. We would NEVER recommend this hotel after our horrible experience of being mistreated. We left extremely disappointed with hotel management and will never return. Do NOT go.
Pre-trip:
My wife and I are over 60 years old and frequently travel, and this is by far the worst experience ever! We usually don't leave online reviews, but this is the first time that I have to ask my son to post this review using his TripAdvisor account. 
Hyatt offers online check in 24 hours prior to arrival. We took advantage of this online tool and confirmed our room.
On-arrival:
We arrived at 11 pm and tried to pick up our keys, but the front desk informed us that there has been a change in our room, and our online check-in has been voided. Our new room was basically a closet with NO BED, NO WINDOWS, and it turns out that the kitchen/toilet was malfunctioning. 
Assistant manager to the front desk, Mr. Matt Palmer, came out to inform us that this was our ONLY OPTION. We were told that this was due to our late arrival (so...online check-in and specifying our arrival time was not enough?) We were told that this will only be for our first night, but the room rate of $175 remains unchanged. As compensation for this ridiculous closet, we were given breakfast for ONLY the next morning and a one-class upgraded room for the remaining two nights (a lofty $35 value - wow, lucky us...). This is completely unacceptable!
We tried to argue and demanded alternatives, but unfortunately, English is not our first language. Mr. Palmer took advantage of the situation and brushed us off. We were left feeling helpless, mistreated with his service, attitude, and inability to deal with the situation. It wasn't until after repeatedly asking "why" did he finally tell us that the hotel was overbooked. Apparently, ONLINE CHECK IN is useless. We just want our original room and will pay the rate that we booked, but this is too much to ask at Hyatt Jacksonville Riverfront.
We had to call our son and ask him for help. After numerous calls to get in touch with Mr. Palmer and what I'm sure was a very frustrating conversation, the best that he could do was to take $75 off the FIRST NIGHT ONLY - that's $100 for a room with no windows and no bed (see pictures). It is clear that Mr. Palmer is grossly incompetent, unable to manage his staff and customers, does not understand basic customer service and hotel management, and cannot deal with situations outside normal/standard business operations. He took advantage of our old age and inability to speak English fluently. Hyatt Jacksonville has the potential to be better without this employee. 
No bed, no window, closet room:
We had slept (or didn't/couldn't really) on a sofa bed. The sofa bed is extremely uncomfortable, and at our age, we woke up suffering from BACK PAINS. That terrible evening weakened our immune system, and we got so sick that we COULD NOT WALK downstairs for the only free morning of breakfast that was offered to us. 
We feel relieved to have returned from Hyatt hell and to have escaped from the unjust treatment and customer disservice. Unfortunately, we are still physically ill and recovering from the emotional trauma. We recommend that you avoid this property at all costs. There are plenty of other wonderful places in the area to stay.