Vijay,
So what version of CRM are you on and what's your number one user complaint? The only reason why I ask is that I support SAP CRM 7.0 here and I have heard about every usability complaint, so I can give you some ideas on how we approached some of the usability concerns.
The biggest problem you have normally with a SAP CRM system is that users don't want to enter any data or they dont' take advantage of features such as saved searches or your master data is not setup in a way to allow for searches and easy access of data. That being said, if you are on EHP1 things like favorites and using the global search(which is also available on 7.0) will make navigation quicker.
What you can't fix is if management wants your users to capture 20 data points in some process it's impossible to make that not-painful no matter how pretty or awesome the UI is. I think that's my biggest problem with UI critics is that fail to address the process issues that sometimes require 20+ data points to be maintained during creation and call the UI painful because they dont' fix the process first. It also stems from the entitlement attitude that assumes that creating a sales order in a system should function exactly like posting a status update on facebook even though it's not possible because the magnitude of the data entry points goes up on a exponetial factor.
Moral of my story: fix the process to be simpler, and then scale down the UI to reflect a simpler process. You can't shove a complex process into a simple screen no matter how hard you try or how easy the data screen technology is.
Take care,
Stephen