More than any previous release, Lion tweaks and extends Mac OS X's interface--often in unexpected ways. With Mission Control and Launchpad, the operating system seems to be be stuck in a tug-of-war between more simplicity and advanced power features. On the upside, though, it means there's something for everyone.
Apple bills Mission Control as "Mac command central"--a new interface that gives you a quick overview of everything that your computer is doing right now.
You can activate Mission Control in at least six ways: A three-finger upward swipe gesture on a Multi-Touch trackpad (you can change that to four fingers in the Trackpad System Preferences pane); a keyboard shortcut, mouse button, or hot corner you've assigned it in that same preferences panel; the Mission Control icon in the Dock; or the Exposé key (F3).
However you trigger it, Mission Control will show you all of the windows (except for minimized ones) that you had open in your current desktop, organized in stacks by application. Each application stack is labeled with the name of the app and its icon; clicking any icon will bring that application and all of its windows to the foreground. You can also click on an individual window in one of those stacks to bring just that one to the front. In addition, you can cycle through all apps in Mission Control by pressing the tilde key (~).
Above those application stacks you see a horizontal array of miniature desktops, representing all of the virtual workspaces you currently have open. By default, you have two of them: your Desktop and Dashboard. (You can change Dashboard from a space into a desktop overlay--the way it appeared in Snow Leopard--in the Mission Control preference pane). Any apps you're running in full-screen mode become spaces unto themselves.
If you want to use more than those two default spaces, it's simple to add a new one: In the Mission Control screen, drag a window or app towards the upper edge of the screen. A new picture of your desktop, overlaid with a plus sign, will appear in the upper right corner; drop the dragged item on top of that target desktop, and a new desktop will be created with that item in it. Another way to create a new desktop: Shift to full-screen mode in any of your apps that support it. To delete a desktop, you hover your mouse cursor over it in Mission Control until an X appears in the top left corner, then you click on the X; any windows or apps left in that space will move to your primary desktop. This won't work with fullscreen apps; to get rid of their spaces, you need to switch to the app and toggle it back to windowed mode.
To navigate between spaces, you again have several options: A three-finger sideways swipe--in Mission Control or from a desktop--will take you to the next space. (As with Mission Control, you can also choose to have that be a four-finger swipe.) You can also click on a space in Mission Control to make it the active desktop. To move a window or app from one desktop to another, you switch to the source desktop in Mission Control, then drag the item up to the thumbnail of the space you want to move it to; you can't drag apps or windows out of those thumbnails.
You can't rearrange or rename spaces, either: You get Desktop 1, Desktop 2, and so on, and that's it. And, unlike earlier iterations of Spaces, you can't arrange your desktops into a two-dimensional grid; you get that horizontal array only. (Hence the sideways-swipes you use to navigate from one space to another.)
However, you can control a couple of aspects of your spaces' organization, thanks to two options in the Mission Control preference pane. By default, "Automatically rearrange spaces based on most recent use" is active, meaning that the space to the right of your primary space will be the one that was last used. (It's a bit like the way Command-Tab always shows the most recent application directly to the right of the current app.) Keep in mind that this option will result in the order of your spaces constantly changing, so if you'd rather keep them static, just deselect this checkbox. Also by default, when you click on a Dock icon for an open application, Lion will shift you to a space where there are already windows for that app. If you'd like to deactivate that, you can uncheck that option in the Mission Control preference pane as well.
If you used Exposé in previous versions of OS X to show all windows in a given application or to show just your desktop, you can still do both. A three- (or four-) finger downward swipe over an app's window will reveal all of its windows; below that you'll see list of that app's open documents. Swiping three or four fingers downwards over an app's Dock icon will reveal all its windows and documents. To show your dekstop, you'll need to do a reverse pinch with four fingers on the trackpad.
My take: Is Mission Control an improvement over Exposé? If you used Spaces in a previous version of OS X, you might like the fact that virtual desktops are now more thoroughly integrated with Exposé. But mixing full-screen apps and spaces is a bit weird for my tastes--especially when those desktops are stuck with those generic labels (Desktop 1, Desktop 2, etc.). I think Apple may be overloading Mission Control by having it manage all of these disparate features. But at least you can take solace in the fact that you can either ignore or in some cases reverse the features you don't like.
Looking at Launchpad, it's as if Apple picked up an iPhone and poured its Springboard interface directly into the nearest Mac: The same app icon layout, folders, and multiple home screens that you get on your iOS device are now on your desktop.
You access Launchpad either by its icon (a brushed metal spaceship) in the Dock or Applications folder; via a three- or four-finger pinch gesture (depending on your setting in System Preferences -> Trackpad -> More Gestures); or hot corner (configured in the Hot Corners sheet that you can access from the Desktop & Screen Saver or Mission Control preference pane). (Fortunately, there's no Launchpad icon in Launchpad itself; that would be weird.)
When triggered, Launchpad zooms in over your current desktop, which fades into the background; it's much like Dashboard, pre-Lion. You see icons for all of your applications neatly arrayed in a grid. To launch one of them, you just click on it.
Launchpad contains all of the programs in your Applications folder (and subfolders in it). And I do mean all of your apps, down to the lowliest installer. The apps that come with OS X itself appear on the first screen, third-party apps on screens after that. New programs downloaded from the Mac App Store go directly into Launchpad, as do those you drag into the Applications folder. If you have a lot of apps, you're going to have a lot of Launchpad screens. You can switch between them with a two-finger sideways swipe, by pressing the left and right arrow keys on the keyboard, or by clicking the little dots that represent your Home screens.
You can make things more manageable by rearranging and organizing all those icons. To move apps, you click-and-drag them; you don't need to click-and-hold until they jiggle before you move them (though you can if you want).
As in iOS, you can also move apps into folders. Creating the latter requires the same simple process: You drag-and-drop one icon onto another; OS X then creates a folder containing them both. It automatically names the folder based on the contents, but you can edit those names. Folders can be rearranged just like app icons, but you can't drop one folder inside another. Unlike iOS 5, Lion won't let you have a folder with just one app in it; as soon as there's just one app left, the folder will disappear and the app will return to the main Launchpad screen. While OS X automatically creates a Utilities folder in Launchpad, containing the apps in /Applications/Utilities, other folders you create in Launchpad won't appear in /Applications.
And, unfortunately, there's no way to arrange apps other than by dragging where you want them; you can't, for example, opt to have them sorted by name. You also can't relegate Launchpad to a secondary display; it only appears on your primary monitor.
If you want to delete an app, you do have to do the click-and-hold dance, and then tap the X that appears in the top left corner. You'll be asked to confirm that you really want to delete it. Bear in mind that you can't delete any of Apple's own apps. Also, if you delete an app from Launchpad, it disappears from the Applications folder too--and I mean it's gone: it doesn't even show up in the Trash. You can always download anything you've purchased from the Mac App Store again; in many cases, those reinstalled apps will retain your data.
My take: In the end, the simplicity of Launchpad icon grid and straightforward app management may appeal most to iOS converts and newer Mac users, but I doubt that most veteran OS X users will find it very helpful. Fortunately for them, it's easy enough to simply not use Launchpad--for now, at least.