Cal vs Annual View
When comparing Cal vs Annual View, the Slant community recommends Cal for most people. In the question“What are the best calendar apps for Android?” Cal is ranked 4th while Annual View is ranked 15th. The most important reason people chose Cal is:
As long as Facebook is already set up on the device, Cal integrates with it with a single click to show all birthdays.
Specs
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Pros
Pro Can import Facebook birthdays with one tap
As long as Facebook is already set up on the device, Cal integrates with it with a single click to show all birthdays.
Pro Clean interface with beautiful background images
The app displays agenda as a combination of events and to-do list items and uses different background images for each calendar day based on chosen themes.
Pro Integrates with Any.do for task management
Cal integrates with Any.do to-do list app for task management.
Pro Integrates with Waze, Uber and Google Maps for navigation
Cal uses Google Maps to show event location, Waze for real-time traffic information and Uber for hailing a car to the event.
Pro Clean widget with event creation
Cal has a good-looking resizable widget that has a shortcut for event creation.
Pro Nicely designed actionable notifications before, during and after meetings
A feature called HeadsUp will show pop-up notifications on phone's homescreen specifically designed for meetings. The content of the pop-up will change based on whether it's before, during or after a meeting.
Before a meeting it will show shortcuts for getting a taxi or a car, seeing attendees, getting directions and notifying other attendees if the user is late via e-mail or Skype. During a meeting it will give shortcuts for setting the phone on vibrate, taking photos, video or audio-recording, adding tasks that will be synced with Any.do or e-mailing a summary. After the meeting it offers sharing task list and scheduling a follow-up.
Pro Predictive text
While adding an event the app will offer suggestions, help invite other people, pick a location, allow making a note and set it as a recurring event if needed.
Pro Voice entry support
Cal allows adding events simply by speaking.

Pro Semester view for displaying 6 months on the same screen

Pro Aligned day number view
This new view aligns months according to days numbers.
Pro Ad-supported, full free version available
A full free version is available now.
Pro Zoom
Users can zoom in on the calendar to get a less noisy view of events.

Pro A comprehensive overview of all events in a given year
The calendar app lays out all events of a given year in a single view with months on x axis and days on y axis. The events can be identified by their color codes and assigned letters.
Cons
Con Cal may give your personal and non-personal information to thrid parties
In the privacy-policy of any.do the following is stated:
"We may share your Personal Information to third parties (with or without compensation) including potential and actual advertisers, sponsors, our third party service providers and partners. We use commercially reasonable efforts to only engage or interact with third parties that post a privacy policy governing their processing of Personal Information."
and
"Use of Non-Personal Information. We may collect Non-Personal Information in order to provide and operate the Service, including for statistical and research purposes; to enable us to further develop, customize and improve the Service based on users’ common preferences and uses; to create and provide our business partners and affiliates with aggregated statistical data and other aggregated and/or inferred Non-Personal Information. We may also disclose Non-Personal Information (with or without compensation) to third parties, including advertisers and partners. We are not aware of the identity of the user from which the Non-Personal Information was collected."
Con Not actively developed any more
Last update was January 2016, and any.do includes a calendar by now.
Con Forces creating an Any.do account
An Any.do account as well as the app has to be used to create tasks, that then will show in the calendar, but cannot be created from the calendar. This can be not only inconvenient but also quite slow.
Con Shallow Any.do integration
Any.do tasks can't be managed from within the app, it requires the user to switch applications.
Con No natural language input support
Cal does not support natural language input, though it may get added in the future.
Con Can be sluggish and buggy
Cal has issues with freezing, sluggishness and other buggy behaviors.
Con Lacks weather information
There is no way to add a weather calendar to the normal calendar view, meaning no weather integration.
Con Noisy UI
With such information density and small scale of each interface element, it can be hard to get a sense of what information is presented.
