Well, this is not really a first impression lar. I actually just install MR CRM 4.0 on a VPC just to get a look at feel of things in MS CRM 4.0.
There is this familar Outlook feel on the workspace.
One of my favourite feature MS CRM workflow, which built on top of Windows Workflow Foundation (WF)
MS CRM is one of the most customisable business application inside Microsoft and I mean besides APIs and SDKs for developers, end users can also customize features within it. Workflow is one great example shown above, which is meant for end user to orchestrate process within the enterprise.
There is this nice article about 11 things to know about MS CRM 4.0 customizations.
Here is the MSDN MR CRM Developer Center. And already 3 books are written about the software.