New Mac users may have trouble figuring out how to uninstall apps. For most apps, it is just a matter of using LaunchPad. This will allow you to easily and cleanly uninstall apps that you obtained from the Mac App Store. You can also usually just put applications in the trash and delete them like normal files. In some situations you may need to run an uninstaller that came with the original app, or follow some instructions at the official app website. But you should not use any third-party special uninstaller or cleaner apps.
LaunchPad is an app launcher that resides in the Dock. From LaunchPad you can view all of your installed applications. You can search for an app and use the keyboard to launch it. You can also organize your apps by re-arranging them and placing them into folders to group them. LaunchPad is also an uninstaller, allowing you to remove apps that were installed by the Mac App Store.
In Mountain Lion you can now quickly search for apps by name in LaunchPad. This, in conjunction with the keyboard shortcut for LaunchPad, can make it quick and easy to launch apps. Organizing your apps in LaunchPad is limited, but the search function makes it irrelevant as you no longer have to look for apps by icon.