I had recently switched from the 30boxes.com calendar to Kiko but hesitated to put too much into Kiko's calendar because I wanted to see what Google was going to produce.
Just when I got used to Kiko…WHAM! Google launches their new calendar. So far it looks simple to use; drag and drop, quick add, reminders via SMS, etc. It also has the ability to share calendars with others. From what I hear, if I have access to more than one calendar, Google Calendar will layer all shared calendars on the same view. If an email is received in your Gmail account that references a date/time, Gmail will ask if you want to add it to your calendar.
So far the only real dissapointment is the lack of an RSS feed. Okay, I found the feed. It seems there is more than one "settings" option, one for all calendars and one on the calendar level. The feeds are on the calendar level.
I exported my Outlook calendar and then imported into Google, it seems that when Google imports your calendar it imports using the Pacific Time Zone, so all of my times are off by 2 hours. You may want to keep an eye on this post to see if there is a resolution prior to importing anything.