Pros:
- non-destructive approach, so your annotations can be always edited (this is actually superb)
- upload to cloud
- support
- good deal terms (expect the con below)

Cons
- it's quite bare bones
- only 1 user (2 or 3 users > no brainer)

Hope you could reach the level of tool called Eagle
which is super intuitive & feature rich "image-swipe files tool" ($29 LTD as well)

https://eagle.cool