Stayed at much better four star sites
We stayed at the Hyatt for one night when we couldn't get into the other hotel we'd been staying at as they were fully booked. Maybe it was just our great experience at the other hotel, but this place was very average.
We booked over the phone using Hyatt's own phone lines. My wife has a scottish accent, which to be honest is not that strong, and found it very hard to be understood by the booking agent. Despite being promised a confirmation e-mail, it never arrived so we popped in on the evening before just to confirm the booking on site and it's just as well we did as it had never come through to them. To her credit, the girl we dealt with at the front desk (Laura) was excellent and personally sorted it out and made sure we were booked in properly, along with an upgrade for the hassle - if it wasn't for her they'd have had a 2/5 rating.
It is the first hotel we've been to where when our taxi pulled up and we started to unload luggage, that the bus boys just stood and watched. We ended up having to wheel four cases and other bags in ourselves, which was terrible service. Maybe it was just the fact that we had shorts on rather than suits that they usually deal with, as we had the same issue when we left the next day. Either way, it's pretty poor standards from a supposedly four star hotel.
The room itself was comfortable if a little dated, and we had a good nights sleep. The shower and bathroom was big too.
The 'decadent' breakfast in the morning was anything but. Some warm bacon and sausages, pancakes that weren't great and a decent selection of fruit and cereals is not what I would call value for money at $26 a head. Especially with dirty cutlery! We did have a snack in Redfield's Bar the night before which was very good (the hot wings are H-O-T hot) with good service, so the food isn't all bad. Location is good, with Seaport Village right next door, trolley stops a few minutes walk away and the Gaslamp Quarter within a five/ten minute walk.
With it being next to the Conference Centre you do get the impression that's all the business they are interested in, and you do just feel like a commodity rather than a customer. A bit more focus on how they treat everyone wouldn't go amiss. 
It's a hotel that ticks the 'average' and 'adequate' boxes rather than 'wow' or 'must stay'. In my opinion, there's far better out there, especially in terms of customer service.