Grand Hyatt a little less than grand
I have stayed at some great Hyatt hotels - even got married at the one in Maui - and the Grand Hyatt's are usually pretty fabulous. 
The Manchester Grand Hyatt has the beginnings of a great hotel - decent location (walkable to the Gas Lamp district, convention center, and shops by the water), nice open entrance area and decent pool area. All of the shops, less one that had a bunch of strange furniture/antique things in it, on my side of the building were under renovation. Strangely, they promoted a coffee shop on my side of the hotel that wasn't in the hotel, and when I finally located it outside the hotel at 2:30 it was already closed for the day. There was one coffeeshop on the opposite side of the hotel. 
The staff was very accomodating (had to change a date for a pre-arranged corporate stay by phone, front desk gave me a packet of tylonal for a headache, and ordered room service a couple of times, bell service was always ready to grab you a cab). 
The rooms were fine. I had a nice view of the pool and harbor. Towels and sheets were 'okay' - not overly plush. Bathroom was okay, had the basic amenities, TV was huge, though had one of those annoying cable remotes that is not super responsive, but had loads of channels. They have mini-refrigerators in every room but no-mini bars (I enjoy having easy access to a quick soda or two w/o having to order room service). 
I was there from Thursday through early Sunday morning and worked in the mornings and evenings out of the room. I was out of the room until about 2p each day and the cleaning staff never made it to my room to clean it. Luckily, I had plenty of towels and other bathroom supplies, so it wasn't the end of the world - just didn't feel as fresh as it should have from a daily cleaning. 
It wasn't a bad experience, just not an amazing 5 star experience. There are several other hotels (the Omni for one) that are pretty amazing if you want a little bit of an upgrade.