On the iPhone version of the app (and oddly missing from the iPad version) is the ability to tap-and-hold on the plus sign normally reserved for adding events to your calendar. When you hold it, a quick entry dialog shows up, where you can enter entire events in natural language. For example, "Dinner on Saturday at 8" will result in an event being created in your default calendar. I'm guessing the thinking here is that the smaller screen benefits more from a quick-entry prompt, where the iPad's larger screen affords you more time to enter all details for an event.
The primary entry method is the same as the iOS 7 Calendar app, requiring you fill out various fields with information such as date, time, duration, location, who the meeting is with, and so on.
Sunrise will automatically pick a unique icon to represent what each event is for (a phone call has a phone icon, for example). The icons are a small feature but make it very easy to identify what each entry is. I find myself only looking at the icons when scrolling through my agenda, and knowing exactly what the entry was without having to read the title.
Calendars you care about on all your devices
Beyond being able to view and manage your agenda, Sunrise also features the ability to import calendars from popular web services such as TripIt, Evernote, Asana, Github, and LinkedIn just to name a few. Again, by allowing users to view important agendas within the same app, Sunrise improves upon Apple's Calendar app, which requires you to subscribe to calendars on a device-by-device basis.
For example, TripIt allows you to import a calendar into the iPhone Calendar app, but viewing the calendar isn't possible on, say, your iPad unless you repeat the TripIt setup process. With Sunrise, once you've connected your TripIt account to the service, anytime you log into Sunrise on another device, your TripIt calendar will be available. The same can be said for all calendars you add to the app.
In addition to popular Web services, Sunrise recently made it possible for users to add "Interesting Calendars" to the app. This means you can add the schedule of your favorite sports teams, a national holiday calendar, moon phases, or any out of 25,000 available interesting calendars to your Sunrise account.
I added the Colorado Avalanche schedule and US holidays to my Sunrise account, but quickly realized I shouldn't add too many more. While I see a lot of value in having the ability to add (what I consider) informational calendars, adding too many can quickly clutter up your agenda, so it's best not to get too overzealous with it.
Needs a search function
My only problem with Sunrise Calendar is the inability to search for a specific entry in my agenda. I think we can all relate to adding an appointment three months in the future and then forgetting the exact day it's scheduled. With most other calendar apps, including Apple's iOS calendar app, a quick search makes finding the forgotten entry possible. With Sunrise, however, you're going to have to scroll through your agenda until you find the entry.
For those who have a full calendar like me, this is a disappointing omission from the app. Through past discussions I've had with the Sunrise team, and seeing Twitter interactions from the Sunrise Twitter account, I know it's a feature the team is aware of and working on for future updates.
Sunrise Calendar is a great app, but the omission of search from the app is a head-scratcher. With the multiple calendar services Sunrise expects people to use in the app, the lack of search features is a big issue. Fortunately, the developers of the app appear to be working on it for a future update.
Even with that in mind, it's easy to consider Sunrise one of the best cross-platform calendar apps. Where most apps fall short is the ability to provide a stellar, consistent experience across multiple devices and platforms. Sunrise's clean interface, easily identifiable icons, and automatic syncing make it a great choice on any platform.