As others have identified here, creating this 'app', even as a simple sharepoint list is pretty basic.
However, when you try to extend this to include a separate 'contact history' record it gets messy really quickly using the tools you have described.
In Notes, I would pop up a dialog, allow the user to enter the call record and flag a few fields - including a body field for a rich description and additional content such as attachments and links, save and close and use an embedded view to show the associated record on the contacts page. I'm sure you would agree that it would take you another 5 minutes of dev to complete this task.
Try doing this in sharepoint and now you're talking about data panels, SQL reads and writes, additional forms in the sharepoint library, etc, etc...
Suddenly you're not talking about a 5 minute RAD job in MS world.