UPDATE: This issue has been somewhat improved upon with Mac OS X Lion. iCal now has a "quick add" button that lets you enter the initial date/time of an event as a phrase. However, editing an existing event uses the same old data entry UI described below. So I can't really say this has been fixed just yet.
UPDATE: OS X Mountain Lion changed the UI for editing date and time fields slightly. The presentation makes it appear that you're editing a single field for each date (instead of three fields per date -- day, month, year). The data entry is still constricted to each component of the date or time. What I would really like to see is support for free-form date entry. So you could just type in "Tuesday" for example, and it would select the next Tuesday relative to today. Entering dates is somewhat easier with the new UI, but not as easy as it could be.
Most of the posts on this site can be classified into two broad categories. There are posts about bugs that break the functionality of an application. These are generally obvious to any user and are not controversial: they need to be fixed.
The other category includes posts about usability problems and design flaws. These are a little more subjective and may be less obvious to some. This post falls into this latter category.
I use iCal a lot and run into this bit of interface all the time (iCal, Mac OS X 10.6.7 pictured):
I'm specifically calling out the "from" and "to" fields of this new event window. Each of these fields has six text fields within it. One for the month, day, year, hour, minute and AM/PM selection. Because of this, entering data into the "from" and "to" fields is tedious.
In recent releases of Mac OS X, Apple has tried to eliminate this problem by offering other means of creating events. You can create an event from an email message, for instance. If the Mail application detects a date somewhere in the body of a message, it will underscore it. You then click this link to be given the option of creating a new event with that date pre-entered for you.
That's a useful trick, but it makes me wonder why it isn't used in iCal itself. Instead of a field made up of six smaller fields, why not have a simple text field you can use to enter a full date. Picture this with me: currently, to enter an end date that may be on May 3, you have to click on the month part of the "to" field, then type "5", then either press the tab key or click into the day part of the "to" field and type "3".
Alternatively, if the "to" field were a simple text field, you could click on it, write "5/3" and you're done. iCal can figure out the rest. Or, you could write "tomorrow". Or "next thu". Remember, Mac OS X already has data-detection logic for finding dates in free-form text... why not re-use it in the app that is all about dates?
This is not a bug — the existing interface works, but it's clunky. This is a usability issue, and one that is tractable. Lets hope Apple decides to fix it. (Oh, and this is not a new idea by any means... a number of calendar tools support natural language entry of dates like this, such as Google Calendar.)