The ability to create custom fields that are easy-to use, yet powerful enough so you can do everything from simple data entry through complex calculations with ease! It's not perfect - there is some lag time when creating or editing reports in sales force analytics which I find annoying as it takes longer than necessary sometimes but this could be my own fault rather than something they need work out of their system (which would have been nice!).
If your looking at having an integrated CRM solution then look no further. You will get all aspects covered including inventory tracking/management etc plus reporting tools built into one platform.