At our organization we switched to Jama starting roughly 2 years ago for our client requirements and I can say that the organization of requirements as well as version control, version history and client sign off features are a few of my favorites.
The one area that I have seen issues in is that getting to the open projects that are pending sign off has been difficult. The default hides them so you have to know to go up and change the defaults to find the signoff requests that are open. Other than I can't really think of anything else.
Very helpful. We are now able to just go to one location and have all the projects organized which before would require many shared internal drives and folder structures as well as documents that could be updated by multiple people at the same time which caused version control problems.
Working on any client implementation with a large number of requirements is a great place to use Jama. The team organization it provides has hands down been a great booster in productivity for my team.