Greetings from the Hyatt Warsaw. I am a newly upgraded Platinum member (free trial status) and I have my first stay in a Hyatt hotel ever
Check-in was fast. I was "upgraded"? from a standard room to a standard room

No problem though because I got lounge access.
The standard rooms are very spacious and nice. I like especially the bathroom with a modern shower and a bath tube. There is a water cooker with tea and coffee in the room.
There are two complimentary bottles of water and three green imported apples (igittttle). There was nothing but some cookies and some soft drinks, tea and coffee in the afternoon. "Happy hour" with food will be in the evening from 6 PM. Complimentary breakfast tomorrow morning in the lounge.
Well, I like the hotel, it's nice modern and spacious. Oh, and also complimentary Internet ^ However, the location is not very central and the perks in other hotels (e.g. Westin, Hilton and Marriott) are usually better in my case.
Summary: I would highly recommend the hotel but there might be better hotels around.