I really enjoyed that you could create your own custom fields for data collection from different websites/platforms such as google analytics or third party software (like Salesforce).
If there is anything we didn't love about GDFF was having to manually change each campaign every single day since our campaigns get changed automatically by GA at least once per hour! This has been resolved now but this definitely needs some improvement in terms of automation. We were using the free version which allowed us to upload only 1GB daily limit data into the platform so had no issues with uploading large datasets.