The ability to create custom reports is great, with this we can pull data from multiple systems into one user friendly report that also has drill down capabilities for detailed analysis of our business processes or other areas within Salesforce where it makes sense as well! It's very easy use once you get used too - not many bells/whistles but I would say they could be added in future releases if needed (but then there are always features missing). We have created several standard monthly summary sales force automation type documents which make up about half way through each month what does happen next quarter compared against previous quarters performance; allowing us an early insight before having any actual numbers at hand by using historical trends.