Flags could be another way to sort and filter entries, and it’s on my todo list. However, I am not sure if flags will necessarily be added as I would more likely add support for tags (one tag could then be ‘Important’).
Also note that you might be able to achieve what you want with the existing features:
- you can ‘rate’ an entry with 0 to 5 stars, and then filter using the filter bar next to the search field
- you could move an entry to a collection called ‘Important’, and then filter by selecting the collection or using the filter bar