The fundamental idea is good. However, the product is consistently buggy, it's missing basic features (and has been for over a year), it's super expensive, support is slow to respond and is unhelpful, and it feels like the product barely improves over time. Can't recommend.
UPDATE: They actually removed some functionality - used to be able to navigate rapidly around the calendar with left/right arrow keys, and now that's just gone for some reason? Contacted support, they say it's not a bug, it's just removed. Lowered from 2 to 1 star - don't use this software