Pros
I've worked and many companies, but this is the friendliest place I've ever worked. Many people at corporate started in the hotels have hospitality in their blood and are a pleasure to work with. The work/life balance was excellent in terms of hours and with work from becoming more and more prevalent.
Cons
Just like any other company, Hyatt reorgs every couple of years, but I went through 4 different reorgs and they were bungled every time. The communication about the reorgs was bad or non-existent, reporting lines were still left in question after reorg announcements (sometimes for months), and there was little explanation of why the department was reorging. The pay is decent at Hyatt, but ask for what you want when you get hired because anything over 4% annual increase was very rare (unless you were promoted). While better opportunities went to high performers, I wouldn't say Hyatt's bonus structure was merit-based. Everyone in the division pretty much got the same percentage of salary bonuses regardless of individual performance.