Has anyone implemented the Service Catalog module?

We are considering implementing the Service Catalog module in our Help Desk environment and are seeking input from people who have implemented the module or have decided against it.

Questions I would like input on are as follows:

Why did you decide for or against Service Catalog?
What benefits have you seen from using Service Catalog?
What challenges have you faced in using Service Catalog?

I really appreciate any input you can offer. My biggest concern is that I don't want to confuse the user especially since they are finally comfortable using SDP and creating their own requests. We have approx. 3000 users supported by about 60 technicians.

Thanks for your help.