Big Day Lite is designed to count down to a specified event or day on your calendar, showing you on a clean, image-focused home screen exactly how much time you have until it arrives. The effect is fun, and while options are fairly limited in this free version, you get a very good idea of how the app works so you can decide if you want to upgrade.
When you open Big Day Lite, it will by default be set to a 2014 trip to Japan. You can change this in the settings menu where you can select a new event of your choosing and the date. The main screen will then tell you how many days until that event takes place. The default background image can be changed, as well, from the airplane wing to something of your choosing. This all works as intended and while it would have been nice to see more options in the free version, the overall effect is what counts and that works exactly as intended.
In the full paid upgrade of Big Day, you can add multiple event countdowns and have access to a few other tracking options -- all very good things for those that are motivated by this type of countdown. If you like the idea of an app that can instantly tell you how many days are left until you go on your next big trip, your child is due to be born, or you retire, this is a solid app, and the free version will do exactly what you need in terms of providing a basic countdown.