First of all, this is my own opinion and only reflects my own experience with the Unicenter Service Desk (USD) from Computer Associates (CA). It is also refered to as CA Service Desk. I have worked with it for about a year. I work as a system developer and use it on a daily basis in my work.

Unicenter Service Desk is a service management tool made by Computer Associates. It is used by both small and large enterprises. Usage areas is knowledge management, service request management and incident and problem management (the ITIL way).

I am now going to talk about the web interface of USD. I believe there is a Java version, but I have never used it. Due to the problems I have found, I can't imagine that the Java version is any better than the web version.

Anyhow. Here are the problems:

1. Unproductive like you would never believe.
A simple task such as reporting an incident to a certain group is a nightmare.
Expect at least 10 times the amount of time that it takes to write an email. And, as has been shown in studies, email is not the most efficient means of communication.
So, naturally, most incidents/changes/support requests are communicated outside of USD at my company and at a later stage forced into USD.

2. The user interface is so badly designed from a User Interface design perspective that it is downright unbelievable that this is used anywhere outside of CA.
And I am not making this up. I have stuidied human computer interaction (HCI), also refered to as man–machine interaction (MMI) or computer–human interaction (CHI).

Buttons have uncommon behaviour. Links does not work the way one expects to. And you can pretty much forget about searching after ANYTHING even thou there is a search button.
You need VERY many clicks with your mouse, and the distance your mouse travels is very long, in a spaghetti path all over the screen area.
Frequent use of popup windows in unexpected places.

Oh yes, you MIGHT be able to search for something if you use some very arcane syntax (which is not documented anywhere as far as I can see) and remember to push "tab" in the right form box, so that a javascript function is triggered that opens a page, which by the way is NOT reachable by any other means.
Of course no AJAX is to be found, but USD relies heavily on Javascript.
In short: A five year old with a basic understanding of dreamweaver could make a better user interface.

3. Customers not viewed as important by Computer Associates. Even the company I work for, which is quite hughe, seems to be looked at by CA as some minor customer. Forget about having any modifications made in this decade.

4. Hopelessly outdated and ugly. Hey CA! Throw in some AJAX for the love of GOD, and remake the user interface from the ground up!

5. Rigid structure. It seems that the structure in USD is somewhat rigid. Or maybe it is too flexible. I dont know. The result is that at my company, USD has grown to a big spaghetti. You have stuff in there not used in the way intended.
If you want to integrate it with something else, you can pretty much forget about that.

6. Unintelligent design. The application authenticates any user using user/password and a long exipre cookie. So ones identity is known.
If you make an incident ticket or any other ticket you need to specify YOUR OWN NAME, which you have to search for (see point 2 above). That should not be necessary as that could be automatically filled in, WITHOUT using a template.
The only thing that is filled in for me when i make an incident is the recipient group. But, there is a catch... it is set to my own group. How often do you assign a ticket to your own group!? Never!
There is also many things you have to specify when you submit a ticket that is not relevant at all, or that is very obvious.

7. Bad email integration. USD "tickets" are entered manually at my company. Email integration is possible but very rigid. You can not easily set up one email address to be used to receive tickets for a certain group.

8. Customer lock-in. No standards whatsoever are used which means that you can not easily switch to some other form of service desk solution.
Instead it seems that my company invests more and more in it, and the cost of a change increases heavily over time.

Conclusion:
Avoid Unicenter Service desk from Computer Associates AT ALL COST!
Any person buying this for a company I would fire on the spot.
Unicenter Service Desk sucks.
Unicenter Service Desk is the worst service management solution there is, so I dont really agree with Forrester on this. They came to the brilliant conclusion that USD was the best service management solution. How could that happen!? Were they blind or maybe someone at Forrester got "an offer they could not refuse", as a certain godfather would have put it?

If you intend to use it to to have some kind of workflow you should only buy it if you want your existing workflow the be slower.
If you want to implement ITIL in your organisation, go for it, but avoid Unicenter Service Desk!

Sincerely
/Jonas