We had a similar experience during the public launch of Google Analytics, Google Base, Google Page Creator or the most recent Google Finance.
Lot of people have already written indepth reviews of Google Calendar. The Screenshots of Google Calendar have been available on TechCrunch much before the public launch.
The user interface of Google Calendar is sleek and impressive. But let's try to compare features of the most popular online calendar service - Yahoo Calendar with Google Calendar. To begin, we'll peform the most common calendar-related tasks using both the online calendar services:
Quickly add an event (like a meeting appointment or task reminder)
Google Calendar: Click a cell in any Calendar view (like Day, Week or Month) - a callout appears - just type the event name with time (optional) like "pick movie tickets 4pm" - Google automatically schedules an event at 4pm.
Yahoo has a more traditional interface with a quick add event box at the bottom of the calendar screen (picture above). Google approach is quicker and since it uses AJAX, the event is added immediately without a page reload as in Yahoo.
Sharing Calendars, XML Feeds
You can share either calendars with public or specific users identified by email addresses. Google does offer a iCal/XML feed that users can subscribe to in their RSS readers. Yahoo has not touched the XML territory yet though it lets you share calendars with a web interface.
Schedule a recurring event (like your son's birthday or parents' anniversary)
Both Google Calendar and Yahoo Calendar offer a similar form when it comes to adding a general event. Yahoo lets you select the type of event like Birthday, Anniversary, Call, etc (that's how it shows those tiny favicons near the event name on the calendar). Second, Yahoo lets you schedule multiple reminders for the same event.
Yahoo shows the "Add Event" in one long page while Google Calendar offers a better design layout. But when it comes to features, Yahoo wins by a long margin here.
Setting events from the past or in future
Yahoo Calendar lets you add tasks or events since the past year until the next eight years. Google Calendar has no such restriction and lets you schedule events starting from 1st January, 1900 until any date in the future. Google Calendar Widgets are more easy to use and flexible than the Yahoo Calendar dropdown.
Navigation: Support for Keyboard Shortcuts
Google has nice intutive keyboard shortcuts like c for creating event, q for quick add, / for search (like Firefox) and Esc to switch to the main view. Yahoo Calendar has no keyboard shortcut support and the only way to navigate is with a mouse pointer.
Google Calendar lets you create multiple calendars like one for your office, one for your family events and one more for scheduling parties among friends. Yahoo does not support multiple calendars yet.
Sending out Notification and Event Reminders
Both Google and Yahoo calendar support notifications by email and SMS. They support most cellular operators in the US and SMS may attract a fee depending upon the service provider.
Google Calendar has a great feature called Daily Agenda that sends you a reminder at 5am of all scheduled events on that particular day. Yahoo has a Daily Calendar Reminders feature that allows you to have an email sent to you summarizing the day's calendar events and items on your Task list.
We've seen Google Finance quickly grab marketshare from Yahoo Finance because of a more interactive interface. The same could be said about Google Calendar. Though both Yahoo and Google offer similar set of features, the interface of Google Calendar is miles ahead of Yahoo Calendar.
Since Google makes it very easy to import existing calendars from Yahoo calendar or Microsoft Outlook, expect lot of people to make a switch to Google Calendar once their servers are ready to take the load. Yahoo, better hurry up.
More reviews by SEW, Matt, Phillip, Mike, CNet, Loren, Dave Nathan and Om